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Note: This is a sub-section of 1886 Institution of Mechanical Engineers
Visits to Works (Excursions) to the London area
WORKS IN LONDON OPENED TO THE VISIT OF THE MEMBERS
The operations involved in the conversion of bullion into coin are mainly interesting to engineers from the precision with which they are conducted. The precious metals are melted with the amount of copper necessary to form the alloys prescribed by law, and are cast into bars 12 inches long and 3/8 inch thick, the width varying from 1.75 to 2.625 inches, according to the coin to be produced. These bars are rolled into strips, from which discs to form the coins are cut; and to show how accurately the rolling must be performed, it may be pointed out that, in the case of the half-sovereign, a variation of 1-20,000th of an inch above or below the correct thickness throws the coin out of the "remedy," or allowance of variation in weight permitted by law. After the blanks have been brought to a definite diameter and annealed, they are automatically placed between the dies, the impression on both sides and the milling on the edge being imparted to the disc in one operation; each press strikes about ninety coins per minute.
The automatic weighing machines, of which there are over thirty, divide the finished coin into "heavy," and "good," at the rate of about twenty-three coins per minute in each machine; and well deserve attention as striking examples of automatic machinery.
Modern coining machinery has been gradually developed from the rough forms used in the seventeenth century, having been greatly improved by Watt, Rennie, Maudslay, and Uhlhorn: that now in use at the Royal Mint was in a great measure renewed in 1882.
ARC WORKS, CHELMSFORD
Crompton and Co
These works were established by Mr. Crompton in 1878 for the manufacture of machinery &c. connected with the rapidly developing industry of electric lighting and electric transmission of power; they have since from time to time been extended.
The main portion of the manufacture consists of dynamo electric machines, of sizes absorbing from 1 to 100 horse-power. From the class of machinery used throughout the works it will be seen. that modern electrical engineering is simply a branch of mechanical engineering, which involves the highest finish in all the parts employed, and in which a host of difficulties have to be encountered owing to the fragility of the materials that most be employed for insulating purposes. Specimens will be noticed of very large dynamo machines, driven direct by high-speed Willans engines; in careful tests these have given extraordinarily economical results, the joint percentage of power wasted in the engine and dynamo together being so small that nearly 80 per cent. of the gross power shown by the indicator diagram has been given out as the net electrical yield of the dynamo; and as the engine itself is extremely economical, the result is that one electrical horse-power can be obtained by the evaporation of 31 lbs. of water in the boiler. Large masses will be noticed of pure soft wrought-iron doubly annealed, which are for the electro magnets; and the new process will be seen of casting copper &c. required for portions of the commutators and other parts of the machines.
In full work 350 hands are employed.
The origin of the Lambeth Potteries may be traced as far back as the middle of the seventeenth century, at which period some Dutch potters settled at Lambeth. Some interesting relics of their quaint and picturesque buildings were to be seen within living memory in the district between Lambeth Palace and Vauxhall, until all were swept away by the formation of the Albert embankment.
The ware made at Lambeth by the Dutch potters was chiefly Delft, although glazed stoneware was also produced at the close of the seventeenth century, and perhaps even earlier. Towards the close of the eighteenth century, the Lambeth Delft ware was confined to very humble articles; and the potteries in the district gradually became devoted exclusively to the manufacture of salt glazed stoneware, producing for the most part vessels for ordinary household purposes only.
In 1834 the establishment of Messrs. Doulton and Watts in High Street, Lambeth, consisted of about twelve persons, working two kilns a week. The progress subsequently made, slow at first though sure, and increasingly rapid during the last fifty years, has resulted in the employment at the present time of about two thousand persons at the Lambeth works alone; while the number engaged at the whole of the firm's establishments in town and country is nearly four thousand.
The surroundings of the potteries in earlier years were very different from the present. A substantial residence adjoined the factory; and attached to it was an acre of garden, long since absorbed by the works, which have increased in size until the factories and studios now cover some seven or eight acres. The first important impulse was received from the application of chemistry to manufactures, whereby a growing demand was created for chemical vessels of stoneware, capable of resisting acids.
In 1846 the manufacture of stoneware pipes for the sewage of towns and for the drainage of houses was commenced by Mr. Henry Doulton, and has since developed into a most important industry. The application of machinery for the purpose was a matter of difficulty and disappointment, which was only overcome gradually; but when the difficulties of manufacture had at length been surmounted, the stoneware pipes were produced with such rapidity as to be reckoned not by feet but by miles per week; at the present time from twenty-five to thirty miles of pipes are made weekly at the firm's works in London, Staffordshire, and Lancashire, and the consumption of clay for these and other sanitary goods amounts to about 2000 tons per week.
Having in 1877 acquired works at Burslem in Staffordshire for the manufacture of the better class of earthenware, the firm have since succeeded in founding a large and increasing home trade, not only in earthenware but also in china; while their recent introductions of novel and artistic decorations have obtained for the Burslem wares a rapidly rising renown.
In the new buildings at Lambeth, the manufacture of fitted sanitary wares has been greatly extended; and several important improvements iu sanitary science have been introduced, including the vacuum water - waste preventor, the automatic flush tank, and modifications in anti-percussion valves.
Apart from general and sanitary wares, the Doulton potteries have within the last fifteen years produced a large amount of art wares, and have provided an eminently suitable handicraft for female workers, in a neighbourhood where such employment was previously unknown. Until 1867 there had been no special art industry at Lambeth, beyond the manufacture of common figured jugs and of garden vases and architectural enrichments in terra cotta. In that year however, the Paris Exhibition gave the first opportunity of making a slight effort to connect art workmanship with the previously rougher productions for domestic use. At that time some fifty or sixty specimens of vases and jugs were produced. These were of simple but good forms, with slight attempts at decoration.
Four years later, for the Exhibition at South Kensington, a much more successful effort was made; and a marked impression was produced by the pieces then shown. In 1872 the regular employment of female artists and assistants was commenced. The increasing experience in the use of stoneware colours and in methods of designing has resulted in the addition of stoneware pate-sur-pate, impasto on faience, a new body called silicon-ware, mosaic decorations, relief and china wares, and various other outgrowths of the original Doulton ware.
In 1882 the art department was centralised in a new building specially arranged with all conveniences for the needs of the work, upon which are now engaged about 200 female artists and assistants.
In December last, the Prince of Wales visited Lambeth Pottery for the purpose of presenting the Albert medal of the Society of Arts to Mr. Henry Doulton "in recognition of the impulse given by him to the production of artistic pottery in this country, and in view also of the other services rendered by Mr. Doulton to the cause of technical education, especially the technical education of women; to sanitary science by the productions of this firm; and, though in a less degree, to other branches of science, by the manufacture of appliances of suitable character."
MAXIM AUTOMATIC MACHINE-GUN WORKS
Maxim Gun Co
This experimental laboratory was established by Mr. Hiram S. Maxim for the purpose of experimenting upon automatic guns, that is, guns in which all the functions of loading and firing are performed automatically by the action of the powder itself (Proceedings 1885, page 167). An automatic gun, which fires ten shots per second out of a single barrel by the action of its own recoil is shown at the works.
LONDON HYDRAULIC POWER COMPANY
London Hydraulic Power Co
This company, incorporated by act of parliament in 1871 and extended in 1884, was established for supplying hydraulic power from high-pressure street-mains. The pressure employed is 700 lbs. per square inch. About 20 miles of mains have been laid in the city of London, in Westminster, and in Southwark; the whole arc kept constantly charged by the machinery at the central pumping station, Falcon Wharf, Holland Street, Blackfriars.
The works have now been in operation for about three years, and with great success. The number of hydraulic machines at present worked from the mains is about four hundred; and 1,350,000 gallons of water at 700 lbs. pressure are being pumped into the mains weekly. The power is charged for on a sliding scale per thousand gallons. The water after use in the machines is passed through a meter, and is then allowed to run into the drains.
The whole of the works have been carried out under the supervision of the company's engineers, Messrs. Ellington and Woodall. The pumping engines and accumulators were made by the Hydraulic Engineering Co. at Chester; and the filtering apparatus has been constructed by the Pulsometer Engineering Co. The power supplied has been employed for a great variety of purposes, including the driving of general machinery with hydraulic engines; but the principal use has been for lifting, and for other machinery acting intermittently.
The chief points of interest in the installation at the central pumping station at Falcon Wharf are as follows. There are four sets of pumping engines constructed on Ellington's system; they are vertical triple direct-acting compound surface-condensing engines; each has one high-pressure cylinder of 19 inches diameter, and two low-pressure cylinders of 25 inches diameter, with three plunger-pumps of 5 inches diameter, the stroke being 2 feet. The cranks are set at angles of 120 degrees with one another, securing a well-balanced engine with the advantages of three-throw pumps. Each engine is intended to pump into the accumulators 260 gallons per minute; under trial 296 gallons per minute were delivered with 205 indicated horse-power, the consumption of feed water being 20 lbs. per I. H. P. per hour.
Steam at a pressure of 85 lbs. per square inch is supplied by steel Lancashire boilers, each 7 feet diameter and 28 feet long. They are fitted with Vicars' mechanical stokers having self-feeding hoppers; and a Green's economiser is placed between the boilers and the chimney. Both stokers and economiser, as well as a lathe for small repairs, are driven by a small Brotherhood three-cylinder hydraulic engine bolted to the boiler-house wall.
The accumulators are two in number, 20 inches diameter and 23 feet stroke, and are loaded to a pressure of 750 lbs. per square inch. The connections are so arranged that either engine can be worked with either accumulator, and the water pumped can be delivered into any or all of the four 6-inch mains which radiate from the pumping station.
The water used is taken from the river through suction pipes laid below the foreshore to low-water mark; and is pumped into tanks over the engine-house, capable of containing about 200,000 gallons, and divided into several compartments for convenience of cleaning &c. The water is pumped either by pulsometers, or by centrifugal pumps driven by Brotherhood three-cylinder steam engines. After having been allowed to settle in the tanks, the water is drawn off from the top through floating suction-pipes, and flows down by gravity through large mechanical filters placed in the engine-room; after passing through these and through a bed of animal charcoal it is stored in the filtered-water tanks, placed over the boiler, from which the pumping engines draw their supply.
There are four sets of filters, 5 feet diameter, each containing two layers of small sponge about one foot in thickness, which are kept compressed under a total pressure of about 7 tons applied by a small hydraulic cylinder above the upper filter chamber. When the sponge becomes clogged with the impurities separated from the water, it is washed by allowing water from the tanks to flow through it to waste, the compressing diaphragms being alternately raised and lowered by the hydraulic cylinder, thus imitating the action of cleansing a sponge by hand in a basin. The eight filtering layers, any of which can be used independently of the rest, are together capable of cleansing about 400,000 gallons of water in 24 hours.
There is an auxiliary pumping station at 2 Philip Lane, Wood Street, Cheapside, containing two boilers of the locomotive type, a 40-HP. non-condensing pumping engine, an accumulator 18 inches diameter and 20 feet stroke, coal bunkers, tanks, &c., and a lift to the street level; all within an area of 29 feet by 15 feet. The whole of the machinery, except the upper part of the accumulator, is below the street level; and the upper portion of the building is let for business purposes.
At Kensington Court, not far from High Street Station, Kensington, is an installation of an entirely novel character. Every house on the estate is fitted with a hydraulic lift, instead of a back staircase; these lifts are all on Ellington's hydraulic balance system, and are arranged so that they can be worked safely without the necessity of employing a special attendant. The doors on the various floors and the valve-gear are arranged on an interlocking system, so that no door can be opened unless the lift cage is at rest opposite to it, and the lift cannot be moved unless all the doors are closed. The pumping station contains duplicate Cornish boilers and non-condensing pumping engines, tanks for storage of water, and two accumulators.
GREAT EASTERN RAILWAY WORKS, STRATFORD
These works, which were opened in 1847, include locomotive, carriage, and wagon departments, and occupy an area of about 48 acres; 12 acres are covered by shops, and 36 are used for yard and siding purposes. The total number of hands employed at the present time is 3,857, of whom 1,697 are in the locomotive, 843 in the carriage, 363 in the wagon, and 954 in the running department. All new rolling stock for the railway is now built here, the average output being one engine, two carriages, and twenty wagons per week; besides which the existing stock of 685 engines, 3,080 carriages, and 14,300 wagons, is kept in repair mainly at these works. About 600 of the carriages are lit with compressed gas, the manufacture of which is carried on at the works.
LONDON CHATHAM AND DOVER RAILWAY, LONGHEDGE LOCOMOTIVE WORKS, BATTERSEA
These works were designed about twenty-five years ago, and were opened in 1862 for the repair of the company's engines and rolling stock. The general plan of the workshops consists of a number of separate buildings with intervening spaces, an arrangement necessarily requiring a good deal of ground. The boundary wall of the works encloses an area of about 18 acres, which however is not all covered, there being room still for further extensions. The shops are fairly convenient in their arrangement and relative positions, though not possessing the advantages of the more modern plan of connected workshops, which are now built in successive bays of one storey; besides being cheaper in first cost, the latter occupy less ground, and afford better facilities for turning out work, by reason of easier intercommunication between the different shops, the transport of material from one to the other being much reduced in consequence.
The workshops are very substantially built of brick, with iron roofs; and evident care has been taken in working out the designs so that the buildings should possess sonic architectural as well as useful features; the exterior surfaces of the walls are well broken up by the buttresses and windows, with good effect, presenting altogether a much less bare and monotonous appearance than is usual in erections of the kind.
The locomotive shops are arranged in the following order, side by side, lying north and south, with considerable spaces between them:—boiler shop; copper-smiths' shop; erecting shop; and smiths shop, which contains also the forge and spring-makers' shop. Facing the north end of these shops, and lying east and west, are the fitting and machine-shop, brass finishing shop, pattern shop, wheel and heavy-tool and grinding shop, engine house and boiler, and range of offices.
These are all contained in a long two-storied building; and the space between this building and the ends of the other shops forms the yard, down which run three lines of rails, having turntables opposite the different shops. The wheel yard and tiring shed are between the erecting and smiths' shop, and immediately facing the wheel shop.
The carriage shops abut on the end of the two-storied building, the principal shop being placed next to and parallel with the smiths' shop. The wagon shop, a recent addition of considerable size, lies immediately behind the carriage shop and in the same line, both being served by the same steam traveller. The roads in these shops are at right angles to the length of the buildings. The saw mill, which has recently been considerably enlarged and contains some of the most modern wood-working machinery, is conveniently placed at one side of the carriage shop, the ends abutting on the timber yard and drying sheds.
The following are the areas of the buildings:-
The work carried out consists principally in the repair and renewal of locomotive engines and tenders. In the carriage and wagon shops have been constructed the whole of the carriages and a large proportion of wagons which have been added to the stock for many years past. The total number of men employed is 668.
The iron and brass foundry is at Dover.
Immediately outside the works is a running shed, planned by the present locomotive superintendent, Mr. William Kirtley, and erected in 1877 to replace an old and inconvenient round shed, which had become too small for the increased stock of engines. The area of the new shed is 5,906 square yards, and it will hold ninety engines. In connection with the shed is a high-level coal- stage conveniently arranged.
BROAD STREET GOODS STATION
Broad Street Goods Station
At this goods station of the London and North Western Railway may be seen hydraulic machinery used in the performance of work connected with the receipt and despatch of merchandise. It comprises hydraulic lifts for trucks and other purposes, hydraulic capstans, and the engine and bailer house.
WHITECROSS STREET GOODS STATION
Whitecross Street Railway Station
This is one of the city warehouses for the receipt and delivery of goods carried by the Midland Railway. The machinery is worked by hydraulic power; and the engines, boilers, hoists, cranes, etc., employed to do the work, are as follows.
There are two pairs of horizontal direct-acting hydraulic pumping engines; one pair has 18-inch cylinders with 30 inches stroke, and the other pair has 16-inch cylinders with 22 inches stroke. Three boilers of the locomotive type cylindrical part 10 feet 6 inches long, and 4 feet 4 inches diameter; fire-box shell 5 feet 6 inches long. Each boiler has 150 tubes of 2 inches diameter, with a heating surface of 853 square feet; heating surface of fire-box 94 square feet; total heating surface 947 square feet. Fire-grate area 18 square feet. Steam pressure 100 lbs. per square inch.
Two hydraulic accumulators: one has a ram 24 inches diameter and 20 feet stroke; the other has a ram 18 inches diameter and 20 feet stroke; water pressure 720 lbs. per square inch.
Nine hydraulic platform-cranes, of which two lift 50 cwts. each, five lift 25 cwts. each, and two lift 20 cwts. each. Two hydraulic wagon-hoists, each lifting 20 tons; three cage-hoists, each lifting 20 cwts.; six jigger hoists, each lifting 30 cwts.; total number of hoists, eleven. Fifteen hydraulic capstans, each having a hauling power of one ton.
Five wagon-traversers, of which two are worked by hydraulic cylinders, and the other three by the capstans.
The pressure main from the engine-house to the warehouse is 6 inches internal diameter. The exhaust water from the machines is returned to a tank in the engine-house to be used over again.
NATIONAL AGRICULTURAL HALL, KENSINGTON
Agricultural Hall, Kensington
This Hall is being erected for agricultural and other exhibitions, similar to those held at the Islington Agricultural Hall. It is situated close to Addison Road Station of the Metropolitan Railway, and occupies 11.5 acres.
The main portion of the building is a great hall, 440 feet long by 250 feet wide, the Islington hall being 384 feet by 217 feet. It is covered by a semicircular arched roof, now in course of construction from the designs of Mr. Max am Ende and Mr. A. T. Walmisley. The roof is 374 feet. long by 170 feet clear span, and is surrounded by a gallery 40 feet wide and about 20 feet above the ground; the clear height to the crown of the roof is about 100 feet. The style of construction has been adapted to the material employed, which consists of rolled iron bars; the various parts accordingly have strongly developed outlines, while the elementary bars are slender.
The characteristic feature of iron structures of this class is the lattice bracing; and in this building the grouping together of systems of lattice bracing strictly in accordance with the requirements of strength is perhaps the most prominent feature, with which is connected an unusual economy of material. The way in which the horizontal thrust of the arches and the horizontal action of the wind are dealt with is of particular interest.
At the top of the roof over the side gallery the foot of the semicircular arched rib is divided into two, one part going down vertically, and the other following the slant of the lean-to roof over the gallery, and then developing into a braced frame of 14 feet effective depth; in this form it continues vertically, and then horizontally underground to join the vertical branch. The traffic on the gallery floor and on the ground floor beneath passes through the loop formed by the two branches, in a manner most favourable to economy of valuable floor space. The inner part of the loop is formed by a cast-iron column, which has a ball-pivot at each end and supports a portion of the gallery floor as well as the greater portion of the weight of the roof. Continuous and independent girders are used in the floor and in the roof, according to considerations of economy.
Another point of detail is the simultaneous application in the semicircular roof of radial and tangential purlins. A novel construction is applied to the screens, consisting of very light lattice girders 4 feet deep, which are suspended vertically, and joined together not in one plane but in corrugations or zigzags. The covering, being glass and zinc as on the roof, follows the corrugations.
ANGLO-AMERICAN BRUSH ELECTRIC-LIGHT WORKS
Anglo-American Brush Electric Light Corporation
In the fitting and erecting shop may be seen Brush and Victoria dynamo armature-cores, old and now and in process of construction; core-winding machines, old and new; details of Brush and Victoria dynamo commutators; erection of dynamos; and tools generally for fitting and erecting.
In the dynamo shed are machines in motion, including a Brush dynamo with automatic regulator for lighting the shops and the testing circuit, and other dynamos supplying current for manufacturing operations.
The winding shop contains armatures and:field magnets in course of winding. In the lamp-fitting shop are search lamps, small and large and automatic; Brush and Brush-Sellon arc-lamps; worm-wheel cutting and emery-grinding machines; a capstan-head lathe, and press tools.
The testing room contains a 20-inch projector, Brush and Victoria dynamos of different sizes, Brush automatic regulators, Brush lamps on testing racks, Brush focussing or head-light lamps in an apparatus showing an image of the electric are magnified about a hundred times, safety cut-out for multiple-series or group lighting, potential alarms, Victoria dynamos working projectors, dynamo driving a centrifugal fan, Wimshurst machines, and transmission dynamometers.
NORTH LONDON IRON WORKS
David Hart and Co
At these works, belonging to Messrs. David Hart and Co., the manufacture of weighing machines without loose weights, a system introduced by this firm, is carried on. A new form of mechanical stoker manufactured here may be seen at work; it is designed for using ordinary small coal, which is fed into the furnace and distributed over it by a small jet of steam.
FOUNDLING HOSPITAL, NEW SANITARY WORKS
Foundling Hospital, London
The royal charter of the Foundling Hospital was obtained in 1739. In 1741 the present site was purchased, consisting of fifty-six acres in Lamb's Conduit Fields; and the western wing was ready for occupation in 1745. The chapel was built in 1747, the organ having been presented by Handel, who added £7000 to the charity by the performances of the "Messiah" alone. The picture gallery was inaugurated by Hogarth, some of whose most celebrated canvasses still adorn the walls. The exhibition of these and other works of art during the reign of George II. was the origin of the present Royal Academy. The hospital provides accommodation for 350 children of both sexes, the boys occupying the west wing and the girls the east.
The new drainage works were commenced in the beginning of the present year, and have just been completed, under the direction of Mr. W. D. Scott-Moncrieff. The sewerage is carried for the most part in cast-iron pipes through the old sewers, which at some points are as much as 7 feet in height. By means of manholes the drains are open to inspection throughout their entire length. The whole system affords an interesting and in several respects a novel example of modern domestic sanitation, carried out upon an extensive scale.
Improved Industrial Dwellings Co
The Improved Industrial Dwellings Company was founded in 1863 by the present chairman, Sir Sydney H. Waterlow, Bart., and is the largest undertaking of its kind in existence. The buildings are erected in every quarter of London, and at present accommodate about 25,000 persons on 38 estates. The total expenditure on land and buildings to 30th June 1886 was £940,900; and the rent roll is about £100,000 a year.
Additional buildings are in course of erection at a cost of nearly £100,000. Each dwelling is self-contained, that is, it possesses complete domestic conveniences for each family, and is wholly separated by party walls from the adjoining dwelling, nothing being used in common except the staircases, roofs, and playgrounds. Little or nothing has been attempted in the way of architectural effects, or in the provision of special mechanical appliances, the primary object being to provide at a moderate cost substantial homes of a comfortable and healthy character, and such as are suitable for the class for whom they are intended.
The latest examples are to be seen at Riles Buildings, for 211 families, in Bell Street and Linton Street, Edgware Road; and at Sandringham Buildings, for 259 families, in the new street now being formed between Charing Cross and Oxford Street.
As earlier examples worth inspecting may be mentioned Lumley Buildings, for 124 families, in Pimlico Road; Coleshill Buildings, for 122 families, in Ebury Street and Pimlico Road; Ebury Buildings, for 135 families, in Ebury Square; and Coburg Buildings, for 108 families, in Coburg Row at the back of Rochester Row, Westminster.
ELECTRIC LIGHTING INSTALLATIONS, COLONIAL AND INDIAN EXHIBITION
Colonial and Indian Exhibition
Garden Illuminations.— These are supplied by Messrs. W. and J. Galloway and Sons, Manchester. About 10,000 incandescent lamps of 5, 10, and 16 candle-power are used; the current for them is supplied by four large compound-wound dynamos of the four-pole type, made by Messrs. Elwell Parker and Co., Wolverhampton, and having a capacity of 50 units each. They are driven by a pair of Messrs. Galloway and Sons' horizontal compound engines, each capable of developing 200 indicated horse-power, constructed specially for running at a high speed, and driving the dynamos without a countershaft; steam is supplied by four Galloway boilers. There arc also 18 arc-lamps of the Brush type on three high masts, driven from a Brush dynamo situated in the west quadrant. For the illumination of the fountains 12 hand arc-lamps are used, each of about 8,000 candle-power, driven by a compound-wound Brush-Victoria dynamo machine.
Internal Lighting of the Galleries.— The motive power for this purpose, supplied by Messrs. Davey Paxman and Co., Colchester, consists of a range of twelve steel boilers of locomotive type, and eight engines, namely two high-pressure coupled engines and six compound engines, together capable of developing 1,200 indicated horse-power. There are distributed in the different buildings about 450 arc-lamps, supplied by the Anglo-American Brush Electric Light Corporation, by Messrs. R. E. Crompton and Co., and by the Pilsen-Joel Electric Light Co.; they are fed by twenty-nine dynamos, of which twenty-three are in use, the remainder being held in readiness as spare machines. In addition to the arc-lamps, about two thousand 16 candle-power incandescent lamps are used for lighting the railway subway, Indian palace, refreshment rooms, and various offices. The current for these lamps is generated by six Edison-Hopkinson dynamos, supplied by tho Edison-Swan Electric Light Co. Tiro batteries of accumulators, manufactured by the Electrical Power Storage Co., each capable of maintaining 400 lamps, are used in connection with some parts of this installation; one of these batteries is fed by an Edison-Hopkinson dynamo, and the second by an Elwell-Parker dynamo.
QUEENSLAND GOLD QUARTZ MILL, COLONIAL AND INDIAN EXHIBITION
Colonial and Indian Exhibition
The gold quartz crushing machinery, erected on the south promenade by Mr. J. N. Longden for the Queensland commissioners, is a full-size working gold mill, in which are shown the whole of the processes from the crushing of the rough quartz to the production of the solid bar of gold. It consists of a battery of five stamp-heads, specially manufactured by Messrs. John Walker and Co., of Maryborough, Queensland. Each stamp-head weighs 800 lbs., and has a drop of 9 inches, and strikes 80 blows per minute. The stream of water supplied to the mill is 500 gallons per hour.
The ore to be crushed, having first been broken into small pieces, is fed into the battery from a hopper. From under the stamps the finely crushed stuff is carried by the stream of water through gratings of 240 holes per square inch, and flows over a series of mercurialised copper plates, through two centre-board wells, and over four ripples. From the tables it is carried by the water over a concentrator of the percussion kind. The concentrated pyrites are fed into a Boss grinding-pan, and delivered thence into two Berdan grinding and amalgamating pans, from which the pulp enters a 7-ft. settling pan as the last stage of the operation. Mercury is used throughout the whole process as the amalgamating agent; and for quickening its action and preventing it from flouring, sodium is employed at regular intervals, on the plan of Professor Crookes, F.R.S.
In Queensland the gold quartz mills run continuously day and night during the six working days of the week, or a total of 144 hours per week. The working power of the five-head mill exhibited is half-a-ton of quartz per hour; its weekly work would therefore be 72 tons. The mills are generally washed up once a fortnight, the whole of the amalgam being collected from each of the pans; this is cleaned and placed in a retort, where the mercury is distilled, leaving the gold in the bottom of the retort in the form of a cake, known as retorted gold, which is afterwards broken up, pelt into a crucible, and smelted into bars of gold for sale to the banks. The distilled mercury from the retort is used over again continuously in the mill. A real cake of retorted gold, being a fortnight's produce from a mine at Charters Towers, Queensland, is shown in the Queensland court of the Exhibition; its weight is 1,707 ounces, and its value £5,923.
ROYAL SMALL ARMS FACTORY, ENFIELD
Royal Small Arms Factory (Enfield)
The arms manufactured at the Royal Small-Arms Factory comprise the Martini-Henry rifle; the triangular bayonet; Enfield breech-loading revolver; Martini-Henry carbines, cavalry pattern and artillery pattern; sword-bayonets of various patterns; lances; leather scabbards for triangular and sword bayonets; new Enfield Martini rifle and carbine; new-pattern cavalry sword; and rifle-calibre machine-guns.
The rifle consists of a barrel screwed into a shoe or body; a butt, and a fore-end. The body contains the breech action, which is the mechanism for closing the breech, firing the cartridge, and extracting the empty cartridge-case.
The breech is closed by a block which swings on a pin passing through the upper rear end of the shoe or body, the recoil being taken by the shoe. The cartridge is exploded by the striker, a direct-acting piston, which is driven by the action of a strong spiral spring within the breech block. A lever in rear of the trigger-guard acts on the breech block, so that the action of pushing the lever forward causes the block to fall, the tumbler to be carried round until the trigger-nose drops into the tumbler-bent, the main spring to be compressed by this motion as the crane of the tumbler draws back the striker round which the spiral spring is coiled, and the empty cartridge-case to be thrown out to the rear. On drawing back the lever, the block is raised so as to close the breech, and the arm is ready to be fired.
The stock is made from Italian walnut, and is in two parts, the butt and the fore-end. The butt is secured in the socket of the shoe or body by means of a screw bolt; and a loop and pin, and two bands, connect the fore-end to the barrel. In the latest pattern rifle the loop and pin have been replaced by a fore-end hook, which engages into a recess in the front of the body.
The lengths of the rifle with bayonet fixed is 5 feet 11½ inches; and without bayonet, 4 feet 1½ inches. Its weight without bayonet is 8¾ lbs.
Stock.— The Italian walnut, of which the butt and fore-end composing the stock are made, is found well suited for the purpose, owing to its lightness, hardness, and closeness of grain. The rough butts and fore-ends, obtained by contract, are examined on arrival, and should any of the following defects be observed, they are rejected:— under size; crooked, at fore-end only; galls, the result of wound in tree; shakes or cracks; rind galls, the result of injury to bark of tree when young; discoloured wood; bines or knots; cross grain; bad quality perished wood; fly and worm holes; impregnation with salt water. All except the last of these defects are readily detected by the examiners; and should the appearance of the wood lead them to suppose that it has been damaged by salt water, a shaving is taken off with a spoke-shave, and is dipped in a solution of nitrate of silver (1 grain in 1 ounce of distilled water), when, should any salt be present in the wood, a white precipitate is formed of chloride of silver. If wood which has been damaged by salt water be used for a stock, it will rust any steel or iron with which it comes in contact; and no method is known by which to remove the salt from wood that has once been damaged.
The butts and fore-ends are usually in a half-seasoned condition when received, and are stacked to season in the stock stores. Green wood requires about three years to season. If it is necessary to hasten the seasoning of the wood, the rough butts and fore-ends are placed in the desiccating room, and subjected to a heat of 60°, gradually increasing to 90° or 100° Fahr. If half dry when placed in the desiccating room, they will be ready for use in about six or seven weeks.
Butt.— The principal machine operations in the manufacture of the butt are as follows:— boring for stock bolt; rough turning; sawing to length; bedding the butt-plate; finished turning; bedding for shoe, and for lever catch-block; counter-sinking and facing for body; hand-finishing.
Fore-end. — The principal machine operations are:— rough turning; grooving for barrel; sawing to length; fitting the nose-cap; finished turning; bedding for body, rod-holder, and fore-end hook; boring for rod; hand-finishing.
Barrel. — The barrel is made of soft or mild steel prepared by the Siemens-Martin process, this metal having been found to be of a very uniform quality. The barrel bars or moulds are obtained by contract in lengths of 15 inches, the diameter for rifle bars being 1½ inch.
Forging. — The barrel bar is heated to a white heat, and passed through the barrel rolling-mill, which consists of ten pairs of rolls arranged alternately horizontally and vertically, whereby it is drawn out in one heat to the full length required of about 36 inches, taper in form, and solid. It is next passed to the Ryder forging machine, where the "Knox form" is forged on the breech end, and the barrel cut to length. It is then passed through a straightening machine, examined for straightness, and viewed as finished-forged.
Barrel Machine-Boom. — The machine-operations consist in clamp-milling for size and length the ends of the barrel; and then drilling up each end about ¼ inch, the diameter of the holes drilled being 0.41 inch. This operation is called "entering the bore"; occasionally a barrel is drilled 1½ inches up at each end, and is very carefully tested to see that the starting of the bore is true and correct. The barrels are then ready for drilling.
Drilling. — The barrels while being drilled are placed horizontally, three in a machine, where they revolve at 940 revolutions per minute, the holes already made acting as guides for the half-round or D bits used at each end in the operation. Underneath the bits is placed a brass lubricating tube of 1/8 inch diameter, through which pure soap is forced at a pressure of 60 to 70 lbs. per square inch; this forces the cuttings or "swarf" out at each end of the barrel. The brass tube is made to oscillate by means of a cam on the shaft connected with the driving pulleys; the same shaft also works the feed slides at each end of the machine. The traverse of the slides is ½ inch per minute.
The bits are run in about 6 inches from both ends; the slides are then drawn back, and the bits pushed to the bottom of the hole, ready to drill another 6 inches length; and so on until they meet at the centre, where as a rule they do not deviate more than from 0.005 to 0.008 inch. The drilling occupies from 35 to 40 minutes. After the barrel has been drilled, the hole is enlarged 0.02 inch in diameter by means of a three-toothed draw-bit; this operation occupies 3 or 4 minutes.
The hole is now broached out with long square bits, on one side of which a strip of oak is placed. Long strips of writing paper are evenly placed between the strip and bit, one upon another, and the bit is run through the barrel until the hole is broached out to the required diameter. This operation is more of a burnishing than of a cutting character, producing a fine, clear, polished surface, down which a shadow is readily thrown by holding the barrel at the proper angle to the light. As shadows thrown off straight surfaces are projected in straight lines on any true surface on which they are thrown, the practised eye can detect any inaccuracy in the bore of it barrel by the appearance of the edges of the shadow thrown down it. In order to ensure absolute certainty that no barrel which has not the bore perfectly true shall be passed on for the exterior to be turned, the following mechanical test has been devised:— a steel rod is stretched taut between two horizontally fixed headstocks, having a collar in the centre and at one end, which fit the bore loosely, so that the barrel can freely revolve on the rod. If the bore is straight, the end of the barrel where there is no collar on the rod will run perfectly true; but, if not straight, it will revolve eccentrically, and its motion is easily detected even by an unskilled person. Every barrel is passed through this test before the turning of the exterior is commenced. The bore is also tested for size by the collars on the roil.
Turning.— The next operation is to support and hold the bore true, while the outside is turned perfectly concentric with it. After a number of experiments to find out a means of fixing a true turned bush or collar on a rough exterior, the present method of rosining sulphur in a liquid state between the barrel and bush was adopted. By this means the exterior of the barrel can be turned perfectly true with the bore, without injury to the inside. The barrel being placed vertically, two plugs, whose centres coincide with the axis of the barrel, are placed in the breech and muzzle; the bush is then held over it, and melted sulphur is poured in between barrel and bush. This gives a bearing for the outside perfectly true with the bore. The barrel is now rough-turned, finish-turned, draw-polished, gauged, chambered for proof, and a screw-thread is cut in the breech end, to take the "butts" which are used for closing the breech during the first proof. This system of turning a barrel enables its exterior to be brought to a definite size, and is greatly superior to the old method of grinding barrels on a large stone, and afterwards striking them sup.
First Proof.- The barrels now undergo the first proof test, which is necessary in order to detect inferior quality of metal, and flaws that do not appear on either the exterior or interior surfaces. The first proof charge is 7½ drams of powder, a lead plug of 715 grains, and over the latter a cork wad ½ inch thick. Twenty barrels are proved at the same time in a cast-iron proof battery.
Finished Milled.— The seat for the front sight is next cross-milled and dovetailed, and the steel for the front sight is sawn to length and brazed on. The barrel is then finished-bored, and set, and is now ready for rifling.
Rifling.— The rifling is done with a cutter having a head of suitable form for the rifling required. This is fitted into a groove cut in a box about 8 inches long, and fitting the bore. It is drawn through the barrel by a rod fastened to one end of the cutter-box, the other end of the rod being coupled into the spindle of the headstock or traversing saddle. On the spindle is a pinion geared into a sliding rack carried by the same saddle. The end of the rack is fitted to slide backwards and forwards along a fixed bar, which can be set at any angle necessary to rotate the spindle and cutter-box to the amount of spiral required. From four to five cuts are needed for each groove; and the cutter is fed up by a screw tapped into the end of the cutter-box, to which is attached a rod working through the centre boss of a band-wheel. A spiral groove is cut along this rod, in which slides a feather fixed in the boss of the hand-wheel, enabling the feed-screw to be screwed in or out by the hand-wheel as required. An index is connected with the hand-wheel, enabling the operator to read off the depth of cut. The barrel is fixed in a rotating chuck, which divided so that any number of grooves required can be cut inside the bore. The rifling is of a uniform twist of 1 turn in 22 inches, or 1.5 turns in the 33 inches length of bore. The form of rifling is that known as the "Henry" rifling; the grooves are seven in number, and are 0.007 inch in depth.
Screwing and Chambering. — The barrel is suspended inside a hollow rotating spindle by a plug inside the muzzle end, running on a plug fixed in the headstock at the breech end. A guide-screw is securely fixed on the rotating spindle, and carries a nut fixed to a traversing tool-holder, which holds a peculiar ferns of chasing tool. The teeth for cutting the screw-thread on the breech end are on the under side, so that, being set over the top of the rotating barrel, the tool can be lifted in and out of the thread which is being cut, in the shortest possible time and distance, without chopping the thread. When the screw is finished, the barrel is driven from it, while the breech end is chambered up for the cartridge. This is an ordinary operation of boring and reamering in a lathe.
Second Proof — The barrel is next breeched up to body, the action put together for proof, and the rifle undergoes the second proof test. The second proof charge consists of 5 drams of powder, and a bullet weighing 715 grains. The barrels are proved in a proof battery somewhat similar to that used for the first proof.
Sighting.— The back sight-bed is soldered on to the barrel, and also secured in its place by two screws. Both the back sight and front sight are adjusted and regulated from the axis of the bore; and when viewing the barrels for sighting, the greatest care is taken to see that both sights are exactly in position.
Browning.— The body and barrel are browned separately. The following is the browning mixture at present in use:— spirits of wine 5 ounces, spirits of nitre 8 ounces, tincture of steel 8 ounces, nitric acid 4 ounces, sulphuric acid 3 ounces, blue vitriol 4 ounces, water 1 gallon. The barrels and bodies are first scalded in a solution of soda for twenty minutes, and are then washed in clean water. The browning mixture is applied, and they are placed in a damp heat for about an hour and a half; after which they are scalded again, and when cool the rust is scratched off. This process is repeated four times, and then the barrels are cleaned off and oiled. The whole operation of browning takes about eight hours.
Body.— The body is made from a specially tough class of mild steel. Bars of this metal, 4 or 5 feet in length, and 2 inches by 1½ inch in section, are obtained by contract.
Forging.— The body is blocked direct off the end of the bar by five blows under a 15-cwt. steam-hammer. The first blow gives a rough figure, and measures off the quantity of metal required. The second blow fullers in the sides of the body, to displace the metal when working the hole through it. The third blow, by means of a chisel in the upper die, splits the metal in the centre, driving out the sides of the body to fill the die, and leaving the impression of the hole, to be made through the body, full size at top. By the fourth blow a full-sized drift, placed in the hole just made by the chisel, is driven clean through, shearing down the sides, and driving through the small piece left at the bottom of the hole. The hole made through the body is now 3 inches by 7/8- inch by 2¾ inches; and the weight of metal wasted is only 3½ ounces. The fifth blow cuts the body off the bar. A mandril is then driven in the hole, and a blow is struck upon the ends to square them up, and the body is now ready for stamping.
Stamping.— The body is reheated, and a cold steel mandril driven into it; and it is then placed under a powerful steam-hammer. On the anvil of this hammer is the lower die of a pair, and the impression cut in the pair of dies is that of the finished size of the forged body. One heavy sudden blow is given, with force sufficient to make the metal flow into every corner of the impression. If this is not done at the first blow, it cannot with safety be attempted by a second blow without reheating; for the surplus metal which flows over between the faces of the dies in the form of a thin fin, chilled and black, would itself absorb the force of a second blow, and perhaps split one of the dies. The body is next annealed, the scale pickled off, fin trimmed, and passed as "finished forged."
Machine Operations.— The hole in the body is first drifted out by means of long drifts slightly tapered, which are drawn through it; and the hole thus produced is used as a starting-point for all the subsequent operations. After drifting, four bodies are placed on a revolving cross-shaped fixing, the arms of which exactly fit the holes in the bodies, while a transverse slide carrying two tool-holders, one on each side, turns up both sides of the four bodies at one operation. This operation leaves the sides of the body equal in thickness, and true with the centre hole. Twelve bodies are next fixed on a revolving head, and the barrel ends are all cut square and true, the stock ends being treated in the same manner. The hole for the barrel is then drilled and tapped; and the burr thrown up by tapping is smoothed down. The face is eased, so that when a gauge is screwed in, it stands exactly true. The body is now placed in a drilling jeg, and the adjusted face is screwed tight up against a rib in the jeg, while the six axis holes of various sizes are drilled, three in each side. The drills run through hardened steel bushes fixed in the sides of the drilling jeg. These axis holes, after being tested for accuracy, become, in conjunction with the large hole in the body, the base points for the remaining operations.
A number of drilling machines now operate to cut away the metal, so as to form the socket to receive the stock butt. The hole is drilled and tapped to receive the screw end of the stock bolt, which secures the butt in the socket. Pins in the axis holes in the left side of the body hold it while the knuckle seat for the breech block is roughly cut out, and the seat milled out square and true.
A number of minor milling, drilling, and tapping operations bring the body into the shape and figure required; and it is then screwed on, or "breeched up," to the barrel. The barrel is now placed vertically with the end of the chamber resting on the collar of a plug, which enters and exactly fits the chamber; and the face of the barrel is drawn tight down on this collar by means of plugs pushed through axis holes in the body. Small mills are now run on a spindle through the block axis-hole, and finish cutting out the knuckle seat of the block to a positive length from the face of the barrel. This length between the knuckle seat of the block and the face of the barrel is rigidly maintained, so as to ensure that the block will interchange or fit in any body; for this purpose each breeched-up barrel and body is accurately gauged with hardened steel gauge-blocks. Care is also taken to see that the striker hole, in the face of the gauge-block, coincides with the axis of the bore of the barrel, so as to ensure the cap of the cartridge being struck in the centre. The barrel and body are now passed on for putting together the action for second proof.
Emery Wheels.- A particular form of emery wheel, called a "rim wheel," has been introduced for finishing up some of the components. Its use has enabled unskilled labour to take the place of a high class of skilled workmen, and the work is better finished. For instance, the slot of the back-sight leaf is first drifted to its true size. By this it is held in a fixing attached to a vertical axis, and both edges with cap attached can be passed across the face of the rim wheels, maintaining it perfectly true, and grinding the edges of the leaf and cap parallel to each other. The sides are done in the same manner.
The method pursued in the manufacture of all the other components is precisely that followed in the case of the body. All the parts are first of all forged in dies, the fin is trimmed off, they are pickled to remove scale, and they then undergo numerous milling, drilling, and other machine operations, until they are brought to the correct figure, when they are viewed, gauged, and either case-hardened, browned, blued, hardened, or tempered, &c., as the case may be.
The barrels of carbines and pistols are treated in the same manner as the rifle barrel. In order to ensure an absolute interchangeability of the various parts, the most exact system of gauging is a necessity; and the strict examination which is enforced prevents the possibility of any defective parts being put into an arm.
The following list gives the nomenclature of the remaining parts of the rifle, and the materials of which they are made. Wrought-iron:— lower band, upper band, block, butt plate, fore-end hook, guard, lever, lever catch-block, nose-cap, nut for upper band, sight bed, sight cap, stock bolt, band swivel, guard swivel, washer for stock-bolt. Steel:— cleaning rod, extractor, front sight, indicator, rod-holder, sight leaf, sight slide, stop-nut, striker, trigger, tumbler. Wrought-iron screws:— two butt screws, guard-swivel screw, lower-band screw, nose-cap screw, two rod-holder screws, upper-band screw. Steel screws:— extractor-axis screw, two fore-end hook screws, indicator-keeper screw, sight-bed screw, sight-cap screw, sight-spring screw, stop-nut keeper screw, trigger screw, trigger-spring screw. Steel springs:— lever catch-block spring, main spring, sight spring, trigger spring. Steel pins:— block-axis pin, lever catch-block pin, lower-band pin, sight-axis pin, upper-band pin.
Case-Hardening.- The breech block, lever, butt plate, and iron screws, are case-hardened. This is done by carefully packing them in iron boxes, in which they are surrounded with bone cuttings or animal charcoal. An iron plate is laid on the top of the box, which is then placed in a furnace and raised to a red heat. The length of time that the various articles are left in the furnace depends on the amount of case-hardening required. When removed from the furnace they are chilled in a tank of cold water. They are then cleaned, oiled, and examined by gauges to ascertain whether the case-hardening has altered their form.
Tempering.— The following components are hardened by being raised to a certain temperature and then cooled in oil:— striker, main spring, indicator, extractor, sight spring, catch-block spring, trigger spring, block-axis pin, extractor axis, sight slide, and steel screws; &c. These are afterwards tempered by "blazing," that is by heating them again until the oil or suet with which they have been covered bursts into a flame.
The following components are blued:— upper and lower bands, upper and lower band pins, guard and band swivels, fore-end hook screws, sight leaf, lever catch-block and pin, guard, nose-cap, rod-holder, &c. These are polished, cleaned with lime to remove grease, and then covered with powdered charcoal and raised to a temperature of about 550° Fahr.
The blade is made of tool or sharp steel, the socket of mild steel, the locking ring of wrought iron, and the locking-ring screw of steel. The blade and socket are welded together, the blade is tapered under a Ryder hammer, and then rolled out in segmental rolls to the required length and a triangular figure. The socket is stamped to size, and then goes through several machine operations, such as drilling, milling, slotting, &c. The blade is hardened and tempered, ground and polished; the socket is browned; the locking ring is blued, and its screw is case-hardened.
ENFIELD BREECH-LOADING REVOLVER.
This revolver differs from the patterns usually met with in having a rebounding lock, and in its method of extracting the empty cartridge-cases. The principal parts are the barrel, the cylinder, and the body. The barrel is 5 7/8 inches in length; the diameter of bore and the form and twist of the rifling are the same as in the rifle. The barrel is attached to the body by means of a screw passing through a knuckle-joint in an arm which projects below the breech end. It is held in the firing position by a spring catch in front of the hammer. The axis-pin of the cylinder is screwed into the body, its point resting in a recess in the joint-arm of the barrel; a projection or boss on the cylinder engages in the same recess. By this arrangement, when the catch holding the top bar is released and the barrel depressed, the cylinder is drawn along its axis; and the bases of the cartridges in the chambers being held by a radial extractor, which is free to move only a short distance along the axis-pin, the cartridge cases are drawn from the chambers to such a distance, that those which are empty are free to fall away, while filled cartridges are held by the bullets remaining in the chambers. The cylinder contains six chambers, and the pistol is loaded in the ordinary way.
The lock action consists of seven components:— hammer, axis screw, trigger, trigger-axis screw, pawl, lever, and mainspring. The mainspring governs the movement of each component. The act of pulling the trigger cocks the pistol and fires it, and upon the release of the trigger the hammer rebounds to half cock. The stock is of walnut, and the remaining parts are of steel. The systemic of manufacture is similar to that of the rifle. The weight of the pistol is 2 lbs. 8½ oz.
The carbines of the cavalry and artillery patterns have the same calibre as the Martini-Henry rifle, namely 0.45 inch, and have also the same twist and form of rifling, but the barrels are only 19 inches in length. The processes of manufacturing the various parts are precisely the same as those for the rifle. The length is 3 feet 1 11/16 inches. The weight of the cavalry carbine is 7 lbs. 8 oz., and of the artillery carbine 7 lbs. 10½ oz.
ROYAL ARSENAL, WOOLWICH
The following is a list of the principal operations carried on at the Arsenal.
Main Factory.— Manufacture of small-arm bullets &c.; squirting rod-lead for ditto. Rockets, war and life-saving. Submarine mines. Metal powder-cases. Zinc cylinders. Metal fuzes of various sorts. Tubes, brass vent-sealing.
Model Room.— Patterns of the various stores manufactured.
Wood Department.— Cutting out and making boxes for small-arm ammunition, and various kinds of chests and boxes for war stores. Wood fuzes. Tent poles, and various parts of heads for detonators &c.
Cartridge Factory.— Casting and rolling metal strip. Operations connected with solid-drawn and rolled cartridge-cases. Making empty small-arm caps &c.
Shell Foundry.— Various operations in connection with moulding and casting projectiles.
Rifle-Shell Factory— Turning and finishing projectiles. Lead-coating rifled breech-loading projectiles. Welding in bottoms on steel tubes to form shell. Forging and grinding Nordenfelt bullets.
ROYAL CARRIAGE DEPARTMENT
Carpenter's Shop.— Dove-tailing and tenoning machines.
Wheel Factory.— Wheel making.
Main Forges.— Stamping by hammer and by hydraulic press. Nut and bolt making.
Foundry.— Manufactures in malleable cast-iron and phosphor-bronze.
Turnery.— Lathes. Worse-wheel cutting. General engineering and other tools.
Main Machine-Shops.— Boring and planing torpedo-tubes. Turning torpedo-halls. Horizontal circular plane. Wall plane. A 4 ft. 6 in. slotting machine. Band-saw for cutting iron. General engineering tools.
Completed Articles.— In mounting ground and in pattern room.
ROYAL GUN FACTORY.
Forges.— Radcliffe steel furnace. Casting steel ingot. Forging at 40-ton and 12-ton and 6-ton hammers.
Turneries.— Turning guns from 68 tons to 2 tons. Milling outside of guns for locking joint. Boring and rifling heavy guns.
South Turneries.— Heavy boring machines. Electric light for examining interior of guns.
Sighting Room— Fitting breech-action to guns. Sighting guns.
Gun-Boring Mill.— Boring and rifling guns. Trepanning ingots and forgings.
Testing Room.— Testing steel for guns by tension, and by flexion.
Field-Gun Section.— Lower shop: milling hood of gun, and milling breech-screws; turning trunnion-arms; turning and rifling field-guns. Upper shop: milling sight-bars, slides of locks, locks, hammers, automatic clamps.
Specimen Shop.— Preparing steel specimens for testing by tension and by flexion.
Obturating Shop. — Making obturating-pad. Pressing pads. Stamping graduations on aluminium strips for sights. Nickel-plating.
Engine Repairing Shop.— Turning, boring, and rifling guns. Testing steel wire, throughout the whole length with 65 tons per square inch; and testing 100 inches length to ascertain elongation and breaking weight.
Outside Shops.— Tempering steel tubes. Boiling steel tubes, hoops, &c. Shrinking hoops on guns.
Pattern Room.— Finished guns.
BECKTON GAS WORKS
Beckton, or "Beek Town" - so called in honour of a former governor of the Gas Light and Coke Company, the late Mr. Simon Adams Beck — is situated in the Essex marshes at a point towards the lower end of Gallions reach of the River Thames, about ten miles east of London. The company's old works, lying almost in the heart of London, did not admit of extension; and when larger premises became necessary, it was considered that the cost of coal delivery might be greatly reduced if the works could be removed some distance lower down the river, so as to avoid the expense of barging and cartage; while at the same time, by having plenty of land, there would be ample space for the storage of such residuals as coke, tar, and ammoniacal liquor.
The present site having been secured, the first pile of the new works was driven on 19th November 1868, at which time Beaten was an uninhabited marshy swamp; but such rapid progress was made that the works were put in operation on 25th November 1870; and so extensive have been the additions since that date that Beckton may now be described as a town in reality as well as in name.
The pier forming the approach to the works from the river is a wrought-iron structure supported on cast-iron cylinders, having a frontage parallel to the river of 800 feet, and projecting forwards 400 feet from the shore into the river. It affords berthing accommodation for five steam-colliers of the largest size; and for discharging their cargoes each berth is provided with three steam or hydraulic cranes and a movable steam-crane; the unloading power is fully equal to 12,000 tons in twenty-four hours. In addition to the pier there are two jetties, and ample quay accommodation for smaller craft.
On reaching the shore the pier joins a viaduct, on the same level and forming a continuation of it. At the point of junction four branches start from the main viaduct, two running along the right-hand side through a series of six retort-houses, and two along the left-hand side through a similar set of six retort-houses. The main viaduct, which has a double line of rails, runs along the whole length of the space between the two sets of retort-houses, a distance of three-quarters of a mile from the river to the end.
The twelve retort-houses are all very much alike. The largest is 510 feet long by 100 feet wide, and. is capable of producing 5½ million cubic feet of alas per day. Running through the house on either side are high and low-level railways of standard gauge; the high-level railway is used for conveying coals from the steamers alongside the pier to the coal stores within the house; the low-level railway is for taking away the coke drawn from the retorts. Locomotives and iron wagons are employed on these railways. In the largest house there are forty-five beds, each containing nine fire-clay retorts of 20 feet length, making a total of 405 retorts. Each retort-house has a complete set of purifying and other plant attached to it: so that the Beckton works may be said to be made up of twelve complete gas works, the smallest of which is of no mean calibre.
The coals are delivered into stores which are conveniently placed in the retort-house, so that the retorts may be readily charged from them. Each retort is charged with about 3 cwts. of coal every six hours. The mouthpieces of the retort are securely closed up with iron lids. The gas as it is distilled from the coal passes up through vertical pipes, fixed at each end of the retort, into a long wrought-iron vessel, rectangular in section, placed on the top of the retort beds, called a hydraulic main; its principal purpose is to serve as a self-acting valve for shutting off the gas when the mouthpieces are opened for charging and discharging the retorts; and it is also here that a large proportion of the tar is thrown down, and some ammoniacal liquor. When a charge is "burnt off," the lids are opened, and what remains, namely coke, is drawn out and deposited on the floor beneath the charging stage; a portion of the coke is used for keeping up the heat of the retorts, and the remainder is loaded up into wagons and taken away for sale.
The gas is withdrawn from the hydraulic mains by exhausters, and is next passed through a series of horizontal cast-iron pipes of 12 inches diameter, called condensers, around which the air is allowed to circulate freely. In this apparatus the tar and ammonia travelling with the gas from the retort-house are condensed, and are rim off into storage tanks.
The gas issuing from the condensers is still very foul; for although nearly all the tar is eliminated, it still contains a considerable quantity of ammonia, carbonic acid, and sulphuretted hydrogen. To absorb these it must be propelled through "washing" or "scrubbing " vessels. The scrubbers are generally in the form of circular towers, about 60 feet high, constructed of cast-iron plates, and filled with coke broken up to a convenient size; on the top is placed brushwood, to act as a distributor for the liquid. The foul gas entering at the bottom of the scrubbing tower and ascending through the coke is met by weak ammoniacal liquor or clean water percolating through the fine interstices of the brushwood, whereby the whole of the ammonia remaining in the gas is absorbed; and the combination is ammoniacal liquor, with which some carbonic acid and sulphuretted hydrogen are also taken up.
The gas has next to pass through eight purifying vessels in the following order: — first through two vessels containing clean carbonate of lime, which removes the whole of the carbonic acid left in the gas; next through two vessels containing oxide of iron, which cleanses it of sulphuretted hydrogen; thirdly through two vessels of lime that has been previously sulphuretted, which removes the greater part of the bi-sulphide of carbon; and finally through two more vessels charged with clean lime, by which all traces of sulphuretted hydrogen are eliminated.
The gas being now as pure as it is possible to make it, and of the required illuminating power, is in a fit state to be delivered for consumption; but before this is done, it is first measured through large station-meters, and stored in gas-holders from which it is pumped out as required. For this purpose there are eight gas-holders at Beckton, from which by means of eight large gas-exhausters on Beale's rotary plan, each capable of pumping 250,000 cubic feet per hour, the gas is propelled along two cast-iron mains of 48 inches diameter, from Beckton to Westminster, picking up from other stations on its way, and filling up other gas-holders along the line of route.
To give some idea of the magnitude of the gas manufacture at Beckton, it may be mentioned that the company have eleven manufacturing stations in all, situated in various parts of the metropolis and suburbs; and the quantity of coal carbonised annually is about 1¾ millions of tons, of which more than half is consumed at Beckton alone.
Tar Distillation.— Tar is a residue resulting from the manufacture of gas: to utilise it is the primary object of tar works. The initial step is distillation, under which the tar gives off its different oils, and leaves a sediment known as pitch; these are called the direct or immediate products. The oils possess many virtues; and the study and practical application of their several properties form the main manufacturing industry of the works. The following table shows the order in which the several products are evolved, and their further development and application towards finished products:—
[See chart in image]
Benzol Plant. — Crude naphtha from tar stills, received into crude stills, gives three qualities in distillation. These are chemically treated and again distilled, the result being crude benzol, which on further distillation gives pure benzol or benzene, and toluol. From these are obtained the aniline dyes.
Carbolic Plant.— Carbolic oil contains carbolic acid, which is obtained by treating the oil with a solution of soda, whereby the original oil is divided into creosote oil and carbolate of soda. The latter when treated with sulphuric acid yields carbolic acid, so widely known as a disinfectant.
Naphthalin Plant. — Creosote oil at an ordinary temperature separates into two substances, one a solid known by the name of salts, and the other a liquid. Creosote oil possesses great preserving properties, and is largely used for pickling timber. The salts are received into hydraulic presses, for extracting the oil remaining in them. The pressed salts are distilled, and after being chemically treated are again distilled; the result is purified naphthalin, which while in a solvent condition is run into candle-shaped moulds, and in this form is known as albo-carbon, the substance used in the albo-carbon gas-burners. In its purest state it is used for colour manufacture.
Anthracene Plant.— Anthracene oil from tar stills, received into shallow tanks for cooling purposes, is then pumped through filter presses; the solid portion left in the presses is called anthracene, of which about 15 per cent. is pure. This placed under hydraulic pressure yields anthracene of which 35 per cent. is pure. Anthraquinone derived from pure anthracene is the foundation of alizarine colours. The oil left after the extraction of anthracene is called green oil, and is largely used for lubricating purposes.
Sulphate of Ammonia.— Ammoniacal or gas liquor, a residue of gas manufacture, contains ammonia, part of which, called free ammonia, is readily liberated by the simple application of heat. The other portion, or fixed ammonia, is evolved by the treatment of the gas liquor with lime. The mixture collected in a boiler is heated by steam, whereby the fixed ammonia is liberated in the form of gas, which is conveyed to a tank or saturator charged with sulphuric acid. The action of the acid on the ammonia results in the formation of a salt which precipitates; this when collected and thoroughly dried is the article known commercially as sulphate of ammonia, so widely used for agricultural purposes.
Sulphuric Acid. — Oxidised sulphur fumes condensed form sulphuric acid. The fumes are obtained by burning copper ore, spent oxide, or sulphur; the two former of these are utilised here. The fumes pass over a vessel containing nitrate of soda and sulphuric acid, and generate nitre gas, which is the oxidising agent. The two gases are together conveyed upwards through a tower into large chambers supplied with jets of steam, which condense the sulphur fumes, thus forming sulphuric acid. The nitre gas after the formation of the acid is still available, and is utilised as follows:- on issuing from the chamber it is passed up through a tower, meeting a descending current of sulphuric acid, which now in its turn becomes an absorbing and oxidising agent. The mixture is conveyed and allowed to fall down the first tower previously mentioned, where it meets fresh fumes ascending on their way to the chamber. The process is thus repeated indefinitely.
These together form one vast dock 2¾ miles in length. They are situated on a wide open reach of the Thames, at North Woolwich, within one hour's steaming of Gravesend. Entering from the east is observed the river wharf, stretching from this entrance in an E.N.E. direction for a distance of 1,120 feet down the river. The depth alongside is 27 feet at low water, so that the largest steamers can lie there at any time of tide to coal, take in cargo, and embark or disembark passengers. Railway lines are laid along this wharf for both passengers and goods, in connection with the general railway system of the country; and a customs and a railway station abut upon the wharf.
The Royal Albert Dock — This dock was completed in 1880, with the exception of the new works, which were commenced in May 1884, and were finished on the 24th of April 1886, by a blasting operation on a gigantic scale. This consisted in the removal of the dock wall forming the north-east side of the Gallions basin, 520 feet long, 38 feet high, 5 feet broad at top, and 6 feet at base, the total weight being 7,850 tons. At either end of the wall, where it met the side walls of the basin, holes were perforated which extended from the rear of the wall to within a few inches of its face, for the purpose of permitting the shattered material to detach itself from the side walls without injury to the latter. For the blasting were used 2,900 lbs. of gelatine dynamite, distributed in 1,430 holes, the charges varying from six pounds at the foot of the wall to half-a-pound at the top. The whole of the charges were fired by electricity simultaneously. With little or no noise, the entire mass was broken up into fragments of from about 5 tons to pieces of the size of road metal, and subsided into the water within a few feet of where the wall had stood. The calculations as to the quantities and distribution of the charges were made with such accuracy that the exact amount of work required to be done was accomplished, and no more.
This dock is entered from the Thames by two parallel and contiguous locks, each 550 feet long and 80 feet wide; the northerly one recently completed has a depth of 36 feet on the sill at trinity high water, and the southerly a depths of 30 feet. These open into the Gallions basin, comprising 15¼ acres of water, 32 feet deep, with six berths for steamers of the largest class. A pumping station has been erected at Gallions, having pumps throwing 125,000 gallons per minute, by which the water in the basin and docks is maintained at trinity high water, or raised above it when required for an unusually deep ship. The passage from the basin into the Royal Albert Dock is by a cut or channel, crossed by a swing bridge. The dock covers 432 acres, of which 87 are water. It is a quay dock, 490 feet wide, with a minimum depth of 27 feet, and has quay berths for thirty-three steamers of the largest class. There are two dry docks, 502 and 410 feet in length, exclusive of a cut of 20 feet at the end of each. The quays are lined with extensive warehouses, along which run railway lines connected with the general railway system.
Since its completion in 1880 this dock has been lighted by electricity, the work having been carried out by Messrs. Siemens Brothers. For the external illumination, twenty-nine powerful arc-lights are provided, supplied with electricity by means of continuous-current dynamo-machines. The arc-lamps are enclosed in lanterns surmounted by reflectors, and are suspended at a height of about 60 feet from latticed iron posts, the light being so distributed that ships are docked and undocked with as much facility by night as by day. For the internal lighting of the sheds, 140 movable arc-lamps of smaller size are provided. The electricity for these is supplied by alternate-current machines, and is conveyed by means of leading wires to suspenders fixed at various points along the sheds, upon which lamps are placed when any part has to be lighted up, an attendant distributing the current where required by means of commutators. To these suspenders can be attached leading wires, for supplying current to portable lamps on board ships loading or unloading alongside the quays. The motive power for the whole installation is derived from four steam engines of 20 nominal horse-power each.
The Royal Victoria Dock. — This dock occupies 200 acres, of which 90 are water. It is a jetty dock, 1000 feet wide, with a depth of 25 feet 6 inches; and has quay berths for twenty-seven steamers of the largest size, as well as for smaller vessels, and for steam colliers at four derricks. It is entered from the Royal Albert Dock through a cut or canal; whilst the passage from it into the river is by means of a tidal basin of 16 acres, and a canal and lock, having a depth of 28 feet on the sill at trinity high water.
The hydraulic machinery at these docks comprises 110 travelling and 92 fixed cranes and jiggers, a travelling coal-crane equal to 20 tons, a floating crane equal to 30 tons, and a pair of shears equal to 60 tons. The four largest steam-tugs are fitted with steam fire-engines; and fire hydrants and engines are provided along the quays. There is a complete system of goods lines throughout the docks, which centres in a goods yard at the Royal Victoria Dock, and thence communicates with the general railway system of the country. Passenger trains run from five stations within, the docks to the city at intervals of a quarter of an hour.
Besides these docks, the property of the London and St. Katharine Docks Company comprises very extensive up-town warehouses at Cutler Street, and a railway depot at East Smithfield, and two other clocks higher up the river, namely the London Docks and the St. Katharine Docks.
The London Docks cover an area of 100 acres, 60 being land and 40 water; they are nearly a mile in length, and have three entrances into the Thames. At the quays, which run along the entire docks, vessels are berthed up to 330 feet length and 24 feet draught.
The St. Katharine Docks occupy an area of 23 acres, of which 10 are water; they have an entrance into the Thames close by the Tower of London, and berth ships up to 250 feet length and 21 feet draught.
The principal works consist of a Tidal Basin, and Main and Branch Docks.
The Tidal Basin has a water area of 19 acres, and a depth of 26 feet at low-water spring tides. Two arrival and departure quays, each 600 feet long, are available for discharging and loading at all states of the tide. At the south-western quay is a coaling jetty fitted with four 30-cwt. movable hydraulic cranes. The lock connecting the tidal basin with the main dock is 80 feet wide and 700 feet long, divided into two chambers of 555 feet and 145 feet respectively. There are three pairs of wrought-iron double-skinned lock-gates; each pair weighs about 240 tons; the width of each leaf is 49 feet, and the depth from the top of the gates to the sill is 44 feet. The gates are opened and closed by hydraulic machinery, which works at a pressure of 700 lbs. per square inch in the mains, the power being supplied from the hydraulic engine-house, supplemented by accumulators placed at the north-eastern and north-western corners of the tidal basin.
In the hydraulic engine-house are three pairs of horizontal compound hydraulic engines of 100 indicated horse-power, which run at 35 revolutions per minute, and are designed to deliver 5000 gallons per hour each; steam is supplied by three Lancashire boilers, 27 feet long and 7 feet diameter. There are two 20-inch accumulators, having a stroke of 24 feet, with wrought-iron casings loaded to give the pressure of 700 lbs. per square inch.
Four dry docks are provided, two having a depth of 32 feet and two of 27 feet on the sills at ordinary spring tides; they are enclosed and divided by caissons. The emptying of the larger pair by pumping out 12,000,000 gallons of water can be performed in an hour. In the pumping-engine house are four centrifugal pumps, making 250 revolutions per minute, of sufficient capacity to raise 650 tons of water per minute; two have suctions of 7 feet diameter, and the other two of 6 feet.
The Main Dock is 1800 feet long and 600 feet wide; and each of the three Branch Docks is 1600 feet long, extending from the main dock in a north-westerly direction; the centre branch dock is 300 feet wide, and each of the two others has an average width of 250 feet. The depth throughout is 38 feet below trinity high-water mark.
There are sixty-one hydraulic travelling cranes, running on rails of 13¼ feet gauge. Each crane is mounted on an iron carriage, through which railway wagons loaded to a height of 13¾ feet can pass. The jib of each crane plumbs at 25 feet from the face of the quay coping. The lifting power is 30 cwts., and the height of lift from quay-level 60 feet. A floating steam-crane is provided, designed to lift and swing 50 tons at 25 feet, or 45 tons at 30 feet; it is capable of placing masts over 100 feet high in a ship of 50 feet beam and 32 feet from the top of the bulwarks to the water-level. There are two land and four floating steam fire-engines.
At the quays, which are 4 miles in length, thirty-one steam vessels of the largest size can be berthed. On the quays of the three branch docks have been erected twenty-two sheds, each 300 feet long and 120 feet wide, the height at the eaves being 12½ feet, and at the centre of the roof 26 feet. Along the quays and in rear of the sheds are laid railway lines, which are in connection with the railway system of the country.
The electric lighting installation, supplied by Messrs. Crompton, consists of 80 arc lamps of 3,000 candles each, and 1,362 incandescent lamps of powers varying from 16 to 22 candles each. Some of the arc lamps are placed on lofty masts on the quays and railway sidings, some in the sheds, and others are portable lamps for lighting ships at the quays. The incandescent lamps are distributed throughout the sheds. The electric apparatus is driven by five engines of 500 effective horse-power in two separate engine-houses.
The whole of the works have been designed and carried out under the direction of the Engineer, Mr. Augustus Manning.
CROSSNESS MAIN DRAINAGE SOUTHERN OUTFALL
Crossness Sewage Works
The Main Drainage Southern Outfall works at Crossness are situated on the south side of the Thames in Halfway-reach; and it is at this point that the discharge takes place into the river of the whole of the drainage from the south side of the metropolis, which consists of a drained area of about 50 square miles.
As the invert of the main sewer, which is 11½ feet in diameter, is at its outlet 28½ feet below mean spring high-water mark, the whole of the sewage has to be raised; and, during the whole of the flood tide and the last two hours of the ebb, it is stored in a large covered brick reservoir of 6.25 acres area, capable of containing 24 million gallons. The reservoir has an average depth of 14.25 feet, and a height of 16.75 feet from invert to soffit, and is sub-divided into four compartments, the level of floor being a little below that of the land outside.
On the north side of the reservoir, and running parallel to it for its entire length, are three large culverts built one over the other. The middle and top culverts are connected to each of the four compartments by eight small culverts, 3¾ feet by 3¼ feet, furnished with sluices: those from the top culvert admit the sewage raised by the pumps into the reservoir; and those connected with the middle culvert discharge the sewage from the reservoir into the river. The bottom culvert is the continuation of the main sewer into the suction wells of the main pumps.
The main engine-house and boiler-house form a handsome and substantial block of buildings. The beam engines, of which there are four, are of the simple condensing type, and of very massive proportions. Each beam has eight pump plungers connected to it, and when working at 11 revolutions raises 4,257 cubic feet of sewage per minute. Each engine is of 125 nominal horse-power, and indicates a little more than double that amount; the pump valves are of the plain hinged type, faced with leather; each set of pumps delivers into its own trough, which is of steel with two air-vessels, and communicates with the top culvert.
Each trough is furnished with a penstock, worked by a hydraulic piston, for which the power is obtained from a pair of duplex pumps capable of maintaining a pressure of 1,000 lbs. per square inch in the hydraulic main. The boilers, of which there are seventeen, consist of twelve Cornish of steel, 6 feet in diameter by 30 feet in length, with corrugated furnace and single-flue tube; and five Lancashire of iron, 7 feet diameter by 30 feet in length, with double flues. The boilers are supplied by two donkey-pumps, with feed-water mostly obtained from two artesian wells sunk for that purpose.
Besides the beam engines in the main buildings, there are four centrifugal pumps, 5 feet diameter, driven by two old broad-gauge locomotives, erected in one of the workshop buildings to serve as auxiliary power in times of flood; the locomotives indicate as much as 300 horse-power each. The pumps are of the vertical-spindle type, and were erected about six years since by Messrs. Easton and Anderson, of Erith.
Full plant is provided for repairs, together with spacious stores and a large water-tank to supply the workmen of the Board, who live upon the works. The water is softened by Clark's liming process. This station is also provided with its own gas works.
These works were opened in April 1865 by H.R.H. the Prince of Wales.
Sewage Experiments.— At the present time experiments are being carried out at this station on the treatment of the London sewage, and one of the four compartments of the reservoir is fitted up and used for this purpose. The whole of the sewage discharged into the river is deodorised by chemicals. The daily average quantity of sewage discharged at this outfall is about 74 million gallons, ranging from 50 million to 150 million gallons in the 24 hours. The system of precipitation adopted involves the treatment of the sewage by means of 3.7 grains of lime in solution and 1.0 grain of proto-sulphate of iron per gallon of sewage.
For the purpose of continuing the previous experiments made at Pimlico, the construction was first authorised of plant at Crossness, capable of treating one million gallons of sewage daily, including the treatment of the sludge by presses, or by other means which might be found advisable. This plant consists of two tanks, each having a capacity of 166,666 gallons. By filling both of these three times in the twenty-four hours one million gallons of sewage can be precipitated. The arrangements for adding the chemicals are as follows.
Lime-water is made in two 1000 gallon tanks, worked alternately, and is agitated by mechanical stirrers, driven by a 6 horse-power Otto gas-engine. The solution of iron is made by hand in a 100-gallon tank. As the sewage flows under the mixing-house, it receives the lime; and, after passing through the stirrers, the iron solution. The treated sewage is then run into the precipitating tanks, where it is allowed to rest for two hours. The effluent, which is of a brownish colour at times, but free from suspended matter, is drawn off from the sludge by means of a falling dam. The sludge is swept into a sump, or underground chamber, which is then closed, and the sludge driven by compressed air into the lime-mixing tank. From thence it is run into the high-pressure receiver or "monte-jus." The connection with the liming tank being closed, and a connection with the press opened, compressed air is let into the "monte-jus," and the sludge is thereby forced into the press at a pressure of 100 lbs. per square inch. The pressing of one charge in the 36-inch press occupies from 45 to 60 minutes.
In order to obtain further information and experience regarding the treatment and disposal of the sludge, one compartment of the main reservoir was afterwards arranged for the treatment of eight million gallons of sewage daily.
The alterations and works involved in this system are:— (1) an iron sludge-trough with falling dams along the length of the discharging end of No. 4 compartment; (2) the erection of plant in duplicate for preparing the lime and iron; the requisite machinery for this purpose is in great part underground, and is covered by two small brick structures, one at each end of the main engine-house; (3) the sludge-main for carrying the sludge from the reservoirs, and lift-pumps for discharging it into the sludge subsiding tanks, which are six in number and are built of concrete, each being fitted with a surface-floating outlet-pipe to carry off the top water; (4) the sludge liming shed and plant; (5) the large 5-ft. press, combined hydraulic and air engine, high-pressure cylinders and 8 horse-power steam-engine.
In addition to the two presses of Messrs. Johnson and Son, a third press, constructed by the Radial Filter Press Co., of which Mr. D. K. Clark is the engineer, has been obtained after very extensive trials.
For the purpose of illuminating the underground reservoir when the men are sweeping out the sludge, a system of electric incandescent lighting has been introduced. The dynamo is driven by the gas engine of the one million gallon plant, and supplies the current for twenty-five lamps. The whole installation has worked very satisfactorily and economically.
The total quantity of sewage treated by the two sets of plant up to the beginning of June 1886 was 490 million gallons. The wet sludge obtained therefrom amounted to 15,100 tons. This quantity, on further settlement in the special subsiding tanks, was reduced to 8,970 tons, of which 5,034 tons have been pressed into 1,470 tons of cake.
The following statement shows the estimate of the Royal Commission, as against the actual results obtained from the treatment of nearly 500 million gallons of sewage at Crossness -
[See chart on image]
Deoderisation- The operations connected with the deodorisation of the sewage are now confined to the application of the chemicals employed, namely manganate of soda, and sulphuric acid; the manufacture of manganate at Crossness is no longer carried on, in consequence of manufacturers now being able to supply a sufficient quantity at low prices. The original furnaces and pans have been cleared away, and the surface made good. The mechanical plant is still standing, the shed in which it is placed being used as a storehouse for reserve stocks.
The two points for observation are the acid tank and the deodorising mills. The acid tank is a lead-lined cistern, 20 feet by 12 feet by 4 feet, and holds, when nearly full, 50 tons of sulphuric acid. The tank is charged direct from the steam barge by means of a pump on the barge. The outlet fills two small chambers alternately, which are used for measuring the quantity of acid withdrawn.
The deodorising mills consist of two pairs of edge-runners or mortar mills, 7 feet diameter, fitted with curtain-guard and conduit. Each pair is worked by an 8 HP. semi-portable engine, which also drives a centrifugal pump to supply water to pans; the system is thus in duplicate, in order to avoid the risk of a complete breakdown in case of accident. A precisely similar set of plant for deodorising is in operation at the Barking outfall from the north side of the metropolis.
The manganate of soda is ground by the mills, through the pans of which a constant stream of water is kept flowing. The solution of manganate of soda so formed flows away to the outlet culvert by means of an open channel. On its way a stream of sulphuric acid is discharged into it, with the result that the manganate of soda (a green compound) is immediately converted into permanganate of soda (a red compound), which has more intense oxidising properties than the simple manganate. This process of deodorisation is in operation at twenty-three stations within the metropolis, in addition to the outfalls.
MESSRS. YARROW AND CO.'S WORKS
Yarrow and Co
The principal things seen here are torpedo boats in course of construction for the British and Foreign governments. In this establishment the entire process is seen of making the machinery and also building the vessels.
SUKKUR BRIDGE CANTILEVERS.
The Sukkur Bridge, the cantilevers of which are being built by Messrs. Westwood, Baillie and Co., London Yard Iron Works, Poplar, is intended to span the Indus at the town of Sukkur, where the river is divided into two streams flowing through the Sukkur Pass and the Rohri Pass. Sukkur is about 300 miles from the mouth of the Indus; and there is at present a steam ferry connecting the railway from Karachi and the railway to Quetta on the west side of the river with the lines to Lahore and Delhi on the cast side.
The only bridge over the Indus at present is at Attock, which is 500 miles north of Sukkur, and near Peshawur in the extreme north-west of India. The Sukkur bridge will therefore form a most important link in the chain of frontier lines now being built, and will afford the same direct communication to the Bolan Pass and Candahar that the Attock bridge does to Peshawur and Cobol.
The Sukkur Pass has already been bridged by three spans of 278 feet, 230 feet, and 93 feet; and the Rohri Pass is to be crossed by the Sukkur bridge now constructing in one span of 790 feet in the clear, or 820 feet between centres of main pillars. The river in this pass is of great depth and swiftness, the current in floods having a velocity of ten miles per bone. The bed of the river and its banks are of limestone rock.
Above and below Sukkur the river is wide and sluggish, flowing like most Indian rivers through an alluvial plain. Owing to the great depth to which the piers would have had to be sunk, and the great length of the bridge, it was thought that a bridge over any wider part of the river would have been more costly than the Sukkur bridge, even with its inevitably large span. The type of bridge to be adopted was the subject of long and careful consideration by the government authorities both in India and in England, the result being the adoption of the cantilever system.
The cantilevers are each 310 feet, and the centre span resting on them is to be a lattice girder of 200 feet. As there is but one span, anchorage has to be provided on each side. The following are the main dimensions of the bridge:— extreme height of cantilever from cinder bedplate, 173 feet; height of rail from under bedplate, 40 feet; length of back guys, 280 feet and 300 feet; width of bridge between centres of main members of bedplate, 100 feet; width of bridge between centres of main members at end of cantilever, 20 feet; width between centres of back guys, 20 feet.
The bridge is for a single line of railway of 5 feet 6 inches gauge. It is to be constructed entirely of mild steel plates and bars, supplied by Messrs. Beardmore, Parkhead, Glasgow, ranging from 1¼ inch to 5/16 inch in thickness, and riveted together with steel rivets. The long struts are rectangular in section; each corner of the rectangle consists of a curved plate with angle-bars on its edges, and the faces of the rectangle are occupied by transverse and diagonal bracing. Longitudinally the streets are curved on all four faces, tapering from the middle towards the ends.
The roadway girders are of steel, 4 feet 6 inches in depth and at a uniform distance of 18 feet apart; the cross girders are spaced 8 feet apart. The floor of the bridge is of corrugated steel plating. The back guys are more heavily strained than any other members; the stress provided for in each of the two guys of the cantilever amounts to 1,200 tons, and arises firstly from a load of 300 tons imposed by the centre span upon the nose of the cantilever, secondly from the dead weight of the cantilever itself, thirdly from a rolling load covering the cantilever, and fourthly from wind.
The anchors are buried in a large mass of concrete, and are built up of steel plates and angle-bars. Each anchor measures 32 feet by 12 feet in a plane at right angles to the line of stress. The total weight of steel in the two cantilevers, including the back guys and anchors but excluding the central span, is nearly 3,000 tons.
Owing to the fact that no staging can be employed in the erection of the bridge in India, and to the difficulty of carrying out work at the site, it was thought advisable to adopt with these cantilevers the same plan that is pursued with all other bridges for India, namely, to erect them in England complete, in order to ensure a perfect fit and accuracy of workmanship in all parts. A great saving of time and expense is thereby effected in the erection of the work abroad, and a much better result is obtained than could be got in any other way. On this plan the last span of the Sutlej bridge, weighing 420 tons, was erected in forty-five working hours. The bridge has been designed by Mr. A. M. Bendel, the consulting engineer to the Indian government.
Among other large bridges built at these works for the Indian government are the Chenab bridge of sixty-four spans, the Empress bridge of sixteen spans over the Sutlej, and the Attock bridge of five spans over the Indus.