Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 132,777 pages of information and 210,006 images on early companies, their products and the people who designed and built them.
Note: This is a sub-section of Practical Engineer
The Practical Engineer published by the Technical Publishing Company. Volume V. 1891.
Many images copied and entered against relevant companies.
A visit of the Institution of Mechanical Engineers to Liverpool in July 1891 gives the following descriptions of the works open to inspection for their members.
This vessel and her sister ship the Teutonic were built by Messrs. Harland and Wolff, Belfast, for the White Star Line, of which Messrs. Ismay, Imrie, and Co. are the managers. These are the longest vessels afloat. Their principal dimensions are: Length over all, 582ft. breadth, 57.5ft. depth, 39.3ft.; gross tonnage, nearly 10,000 tons.
They are built of Siemens-Martin steel, and propelled by two independent sets of triple-expansion engines, driving twin screws with manganese-bronze blades, and developing 18,000 indicated horse power. In each set of engines the cylinders are 43in., 68in., and 110in. diameter with 5ft. stroke. Both engines and boilers are set below the water line, like those of a man-of-war, for enabling the vessel to act as an armed cruiser in time of war.
The two sets of engines are separated by a longitudinal bulkhead, which gives additional rigidity and strength to the vessel, and also adds to her safety for being fitted with twin screws, in the event of the disablement of one set of engines, the other set can carry her to her destination. The Majestic and Teutonic have only three masts, instead of four, as has been usual in the White Star steamers the masts have no yards, and carry only fore and aft steadying sails. These vessels are so constructed that at 48 hours' notice they could take their places as armed cruisers carrying twelve 36-pounder breech-loading guns at least half their crews are naval reserve men. A vessel thus armed, and steaming twenty knots an hour, would be most valuable as a convoy, scout, or blockade runner in time of war.
Each ship made ten passages to and from New York during 1890, averaging about 5 days 22 hours either way.
The White Star Line, starting with the Oceanic in 1869, now comprises a fleet of sixteen vessels and with the Britannic and Germanic in 1875 shortened the voyage across the Atlantic to less than eight days, as against the ten and twelve which were then the rule.
The main building of the Walker Engineering Laboratories is three-storeyed, built in terra-cotta and grey brick, of which the rest of the college buildings will be constructed. The new infirmary, as well as the chemical laboratories, are already completed: and the new library, clock tower, and other portions of the new arts wing are in process of construction.
The vestibule of the laboratories is reached through an arch of terra-cotta work of Norman character, beyond which a few steps lead up to the main entrance of the hall, separated from it by a screen of folding doors. The hall has walls decorated with faience work, and a floor paved with a mosaic pattern. On the right is a balcony looking over the main laboratory, and arranged so that the work going on may be seen without the necessity of entering the laboratory itself. Passing straight onwards, on the left is the students' cloak and dressing room, round which runs an iron gallery, whereon are lockers for coats and clothes suitable for workshop use.
Descending a few steps, immediately in front is the wood-working department, separated from the main building by a fireproof floor; to the right is a side door into the main laboratory and workshop. The portion devoted to laboratory work is screened off from the workshop. In the laboratory is a 100-ton Wickstead testing machine, fitted with alternative centres, by which it can be converted into a 20-ton machine. The details of this machine are described in Professor Hele-Shaw's paper. Other smaller machines for testing the strength of materials the properties of lubricants, &c., are also placed here.
The main workshop is well stocked with tools. At the end is the dynamo for generating the electric current, by which the main building can be lighted. In common with all the machinery in the place, the dynamo is driven by a vertical engine of 40 horse power, which actuates the main shafting that runs along the centre of the laboratory; the counter- shafting for the various machines is on either side, attached to the main girders. Above is a travelling crane, running from one end of the laboratory to the other. Near the vertical engine is the experimental marine engine, of which a description is given in Professor Hele-Shaw's paper. Near this engine is a large lathe, a shaping machine, a drilling machine, and a Worthington pump for hydraulic experiments.
In the adjoining boiler-house is a Robey boiler of locomotive type for supplying steam to the smaller laboratory engine; and a larger marine experimental boiler for the larger engine. Also one of the experimental tanks for measuring feed water, &c.; and a small forge and anvil; and a furnace for melting brass and iron in connection with a small foundry. Beneath the floor are the coal bunkers, and the three furnaces by which the whole building is heated on the high-pressure hot-water system of Messrs. King, of Liverpool.
In the wood-working room, which is 100ft. in length, is a range of carpenters' benches, and along the wall a row of ten wood-working lathes, driven by a 12 horse power gas engine, which also actuates a general joiner, consisting of a circular saw, wood-planing machine, and other wood-working tools, such as a band saw and hand planer; also an emery grinding machine, and a dynamo by which the carpenters' shop is lighted.
The museum on the first floor is reached either by the stone staircase from the main hall, or by a spiral iron staircase from the main laboratory. It contains already some cases, although at present it has but few models or specimens. It is hoped it will become of great importance as an educational feature, for showing not only engineering models, but also specimens illustrating corrosion and fracture, and wear resulting from friction, and also examples of the various materials used in engineering construction.
Such museums, although occupying an important place in similar institutions abroad, have not at present been made a sufficiently prominent feature of engineering colleges in this Country.
The lecture hall, reached from the museum, has been well fitted as regards arrangements of the blackboard and lecture table and lantern. It is found to have excellent acoustic properties, and there are separate desks for 128 students.
In the apparatus room, adjoining the lecture hall, models for lectures are made. Next to it is a large classroom. Beyond is the professor's private room, with anteroom, forming the assistant's room. The passage from the museum leads by a staircase up to a mezzanine floor, from which the upper tier of seats in the lecture hall is reached this floor overlooks the museum from a balcony. At the end of the top corridor is the drawing hall, occupying the whole width of the building, and well lighted on the north, east, and west the artificial lights consist of gas pendants, not combined with electric light, as elsewhere. Separate electric lights hang from the roof over each of the fifty drawing tables, of which each student has one. Adjoining the drawing hall is the lecturer's room, and the private room of the assistant lecturer on engineering; also a smaller classroom and the students' common room. Above the latter, in a portion of the roof, is constructed a photographic and dark room also a room lighted by a skylight, where copies of engineering drawings and tracings may be made.
North Dock Works.— The system of docks comprising the Hornby, Alexandra, and Langton Docks, connected with the river by the Canada Basin, is that most recently constructed for the accommodation of the largest class of vessels, and is now used by the great transatlantic liners. The area of the Alexandra Dock, the largest of the group, is about 44 acres, and its quayage 4,000ft. The quays are provided with sheds for the shelter of cargo; these are for the most part 95ft. wide, in one span. On the north quay of the Langton Dock is a double- storey shed, with roof cranes of the kind which will be seen at the Toxteth Dock.
The Canada Basin, and the approaches thereto, are kept clear of silt by an elaborate system of sluices in the side walls and floor of the basin, and in the base of the north and south jetties at its entrance. Through these large volumes of water are allowed to flow at low water, to sluice away the silt deposited from the highly-charged water of the estuary, which tends to accumulate rapidly in all open basins. The largest of the main sluicing culverts is 13ft. wide by 15ft. high the outlets in the side walls are 4ft. by 4ft. and 6ft. by 6ft. The under-floor pipes are 8ft. diameter, and the up-shoots from them 3ft. diameter, each having a cover to assist in distributing the water around it. The sills are laid at a depth of 12ft. below "Old Dock Sill" datum, giving a depth of water of 31ft. on the sill at high water of ordinary spring tides. The gates to all the entrances and passages are of greenheart timber. The dock gates, bridges, capstans, sluice machines, &c., are worked by hydraulic power, the pressure water being supplied from the centre at the Langton Graving Docks.
Langton Graving Docks.- These docks are two in number, each 950ft. long, and having a pair of inner gates by which it can be divided into lengths of 450ft. and 500ft. The chambers of these docks are built entirely of concrete; only the quoins, &c., at the entrances are of dressed stone. In many cases the water can be run off from these docks at low water; but pumps have to be provided to empty them on unfavourable tides, and also to clear them of leakage on all tides. The wells, two in number, are situated in the engine house between the entrances.
Each well has a turbine pump for dealing with the bulk of the water which cannot be run off, and a set of chain pumps to take the leakage. These are driven by two horizontal Corliss-valve jet-condensing steam engines, made by Messrs. Hick, Hargreaves and Co of Bolton, who also supplied the turbine pumps.
Hydraulic Power Centre. In the same block of buildings are situated the main hydraulic pumping engines supplying pressure water to this district of the Dock Estate, at a pressure of 700lb. per square inch. These engines are horizontal condensing engines of 350 indicated horse power, made by Sir W. G. Armstrong and Co, who also supplied most of the hydraulic machinery for this section of the dock. The accumulator at the east end of the building is 24in. diameter and 40ft. stroke.
100-ton Crane. This crane, situated on the south side of Langton Branch Dock, lifts the weight by the direct action of an inverted hydraulic cylinder, in which the stroke of the piston is 50ft.
30-ton Crane.— Situated between the graving docks, this crane has the special feature that it is capable of being moved along the quay, and of taking up a position to serve one of the four graving dock chambers. Both these cranes were made by Sir W. G. Armstrong, Mitchell, and Co.
Canada and Huskisson Docks Improvement Works — Works are now in hand with the object of making the Canada and Huskisson Dock available for vessels of the largest class. The scheme includes the deepening and lengthening of the Canada 100ft. lock, the improvement of the west quay of Canada Dock, the construction of a new branch dock, and the construction of a new deep-water half-tide dock on the site of Sandon Basin and Wellington half-tide dock, which will serve as a vestibule to the altered Canada-Huskisson system, and to the docks lying to the southward, in all of which water for vessels of the deepest draught will be maintained at all times.
A new deep-water graving dock will also be constructed. The excavation of the branch dock and formation of its walls in concrete are now in hand, and the north side of No. 2 Huskisson Branch Dock is being extended 230ft. as part of the new dam between the Huskisson and Canada Docks, through which a passage 80ft. wide will be formed. The existing dam and passages in line of Battery Street will be entirely removed. Work is now also being carried forward at the west wall of Canada Dock, the Canada 100ft. lock, and the approaches thereto in the Canada Basin.
Coburg Pumping Station.— This installation of pumps has been provided to maintain water in the old docks, from Brunswick to George's inclusive, 80 acres in area, at such a level as will allow of their use by vessels of deep draught. Without this aid they would not be available on neap tides for any but light-draught vessels, as the sills and bottom of the docks are at a comparatively high level, and as in the approaches to their entrances the Pluckington Bank rises to about the level of the present sills, which forbids their being lowered.
The Brunswick-George's group is therefore now worked as an impounded system, approached by deep-draught vessels by way of the Union Dock, which serves as a lock, and of the chain of new docks southward thereof, whose sills are laid at the low level of 12ft. below Old Dock sill. Light-draught vessels, however, can enter as heretofore by way of the outer docks, Brunswick half-tide dock, Coburg Dock, Queen's and Canning half-tide docks, and can be locked up to the level of the inner docks.
There are at this station three centrifugal pumps of the Invincible type, made by Messrs. J. and H. Gwynne. Their principal dimensions are as follow: Fans 90in. diameter, suction and delivery pipes 54in. diameter, pump casing 16.5ft. diameter. They are driven by vertical inverted compound surface-condensing direct-acting engines arranged tandem fashion, independent of each other, and having the following dimensions: High-pressure cylinder, 22in. diameter; low-pressure, 40in. diameter; stroke, 30in; revolutions, 90 per minute. Steam is supplied at 100lb. pressure per square inch from five steel Lancashire boilers, 30ft. long and 7ft. 6in. diameter. The pumps have delivered about 1,200 tons per minute, or 400 tons per minute each pump, and are fully capable of doing the work required of them.
Double-Storey Shed, Toxteth Dock.— The double-storey sheds have been designed to allow of the rapid discharge of cargo from vessels, for which purpose large area of shed floor is required for the sorting, &c., of cargo. The chief dimensions of this shed are: Length, 1,360ft., with 95ft. outside; it is divided by brick walls into five compartments. The ground floor is partly paved with granite sets, and partly asphalte on macadam. The upper floor is on wrought-iron main girders and floor beams, covered with buckled plates, on which are laid tiles set in cement.
This floor is supported by brick side walls and piers. The roof is of light wrought iron, supported on wrought-iron columns. For the discharge of goods from the ships to the upper floor, special hydraulic cranes have been designed by Mr. Lyster. They can each lift 30 cwt. with a radius of 35ft., and are arranged to travel on rails laid along the ridge and eave of the shed, so as to be brought into position to suit any hatch of a ship. In order to allow of goods being discharged at any point, the dock side of the roof is carried on iron columns, and continuous iron doors are provided. Hand jiggers are placed on the road side of the upper storey, and over hatchways, for lowering goods from the upper floor down into carts.
Petroleum Stores at Herculaneum Dock.— There are sixty magazines capable of holding in all about 60,000 barrels. They are excavated in the cliffs on the east and south quays of the Herculaneum Dock, and are separated from each other by walls of solid rock, and are provided with wrought-iron doors. The sills of the doorways are raised toll a height of 4 ft, above the floor, so as to render each magazine capable of containing the whole contents of the barrels in bulk, in case any accident should occur.
On the land to the south of Herculaneum Dock four petroleum tanks have recently been provided, two of 2,000 tons each, one of 2,500, and one of 3,000 tons. Each tank is surrounded by a concrete embankment, forming a moat capable of containing the whole contents of the tank. For the reception of the oil, the tank ship bringing oil for any of these tanks is berthed on the west side of the Herculaneum Branch Dock, and by her pumps discharges her liquid cargo through pipes laid underground into the land tanks, the bottom of which is some 15ft. above the level of the dock quay. For delivery of oil, pipes are laid from the tank into filling houses on a terrace lower down the slope of the land. Here the barrels are filled by gravitation and loaded upon carts and wagons direct from the floor of the filling house; or bulk wagons standing on the rails may be filled direct by a pipe from the filling house. Empty barrels that are to be filled are brought to the dock quay, and then lifted by a barrel elevator worked by a gas engine. From the top of the elevator a runway laid at a suitable slope leads to the several barrel yards, into which the barrels are delivered for cleaning, coopering, glueing, and painting, before filling.
THIS railway connects Liverpool with Birkenhead by a tunnel under the Mersey, which is here 1,320 yards or three-quarters of a mile wide. It begins at the Central Station of the Cheshire Lines in Liverpool, and is constructed almost entirely in tunnel, lined throughout with brick in cement, and laid with a double line of steel rails, of bull-head section, weighing 86lb. per yard, on sleepers spaced 2ft. 3.5in. centre to centre. Under the river the tunnel is in sandstone rock, with a cover of 30ft. to 35ft. between the river bed and the top of the tunnel. The lowest level is 145ft. below mean high-water mark, and the gradient on the Liverpool side is 1 in 27 for a short distance.
The tunnel is drained by a heading beneath of 7ft. 4in. diameter, through which the water runs into two pumping shafts, one on each side of the river, where it is raised 170ft. There are three pumping engines at each shaft, one a compound overhanging-beam engine of 200 horse power, with double-acting cylinders of 36in. and 55in. diameter and 10.5ft. and 13ft. stroke respectively, working plunger pumps of 40in. diameter and 15ft. stroke.; and two compound horizontal engines, working other double-lifting or bucket pumps of 30in. diameter, in balanced sets from quadrants. One of the horizontal engines has cylinders of 20in. and 35in. diameter and 6ft. stroke in the other the cylinders are 33in. and 60in. diameter with 10ft. stroke; both are fitted with differential valve gear.
For the ventilation of the tunnel four Guibal fans are kept constantly at work; two are 40ft. diameter and 12ft. wide, and two are 30ft. diameter and 10ft. wide; one of each size is erected at Liverpool and one at Birkenhead. The larger are each driven by a tandem compound condensing engine of 120 horse power, having cylinders of 20in. and 33in. diameter and 2.5ft. stroke; and there is a stand-by non-condensing engine with single cylinder of 33in. diameter and 2.5ft. stroke. The smaller fans are each driven by a similar engine with cylinders of 15in. and 24in. diameter and 2ft. stroke and the stand-by engine has a cylinder of 34in. diameter and 2ft. stroke. The four fans, running at about 45 revolutions per minute, together exhaust about 580,000 cubic feet of air per minute, equal to about one-seventh of the total capacity of the tunnel. The exhaust from a separate heading or drift of 7ft. 4in. diameter, running alongside the tunnel; and frequent openings from the tunnel into the fan drift, which are fitted with sliding doors, afford the means of distributing the exhausting action as desired. Fresh air is admitted into the tunnel at the stations.
On each side of the river three hydraulic lifts are provided for raising passengers from the underground stations to the street level; the height of lift is 76.5ft. in Liverpool, and 87.5ft. in Birkenhead. Each lift accommodates one hundred passengers the average speed is 120ft. per minute. The rams are composed of steel tubes 18in. outside diameter, screwed together in lengths of 11.5ft.
The average pressure is 70lb. to 75lb. per square inch, obtained from water tanks at the top of lofty towers. The tanks are kept full by small pumping engines, and the same water is used over and over again continuously. The lifts are balanced to the extent of about two-thirds of the weight of their cages and rams. The cages are lighted by ordinary gas supplied through flexible tubes.
The locomotives in working order weigh nearly 68 tons, having inside cylinders 21in. diameter by 26in. stroke, and six coupled wheels of 4ft. 6in. diameter, and a four-wheeled bogie, making ten wheels in all. The carriages are lighted with compressed oil gas, and fitted with continuous automatic vacuum brakes. About three hundred trains pass through the tunnel daily, the maximum service being a train each way every five minutes.
The preliminary works were begun in December, 1879, the main works in August, 1881, and the traffic commenced in February, 1886. The engineers are Sir James Brunlees and Sir Douglas Fox, assisted by Mr. Francis Fox.
The Liverpool Electric Supply Co, supplying electric light throughout a large portion of Liverpool, has three central stations, of which the most complete is situated, with the offices and works, in Highfield Street, close to the Exchange Station of the Lancashire and Yorkshire Railway. The mode of supply is by low-tension direct current, at a pressure of 110 volts. Each set of machinery consists of a dynamo, driven by a Willans compound engine fixed on the same bedplate, and is capable of maintaining 1,500 incandescent lamps of sixteen candle power.
The dynamos are all arranged to run in simple parallel. Steam is supplied to the engines by double-flued or Lancashire boilers, 28ft, long and 7.5ft. diameter. During the hours of least demand the engines are stopped, and the current is supplied from accumulators. The cells used are made by the Electric Construction Co and the Crompton Howell Electrical Storage Co, and are contained in boxes 4ft. long, 124 wide, and 13in. deep. The distributing mains are laid underground in iron troughs, filled in with bitumen, on the Callender plan. More than twenty miles of mains have already been laid; and current is now being supplied sufficient for 13,000 incandescent lamps of sixteen candle power.
Between fifteen and sixteen miles of hydraulic mains are at present laid in Liverpool, extending from Toxteth Dock at the south, to Bootle at the north, and as far back from the river as St. Anne Street; and extensions are being made as required. The mains in the streets vary from 6in. internal diameter in the principal lines, to 2in. for service pipes into consumers' premises. They are of cast iron, of standard sizes, with strong flanges, the joints being bored and turned and made with a gutta-percha ring. The mains are laid in circuit, as far as possible; and there are controlling valves at about every 400 yards, so that any section can be isolated for repairs or extensions. The pumping station is situated in Athol Street, on the west bank of the Leeds and Liverpool Canal. The water for the mains was at first drawn from the canal, and passed through tanks and filters provided over the engine and boiler houses; but an arrangement has since been come to with the Liverpool Corporation, and water from their mains is now used, which obviates the necessity of filtration.
The mains are kept charged by powerful pumping engines. There are already at work two sets of Ellington's triple compound condensing engines, of 200 indicated horse power each, made by the Hydraulic Engineering Co, of Chester. A third set is now in course of construction, and provision is made in the engine-room foundations for more as they may be required. Steam is supplied by three Lancashire boilers, 30ft. long, and 72ft. diameter, fitted with Vicars' mechanical stokers, which are driven, along with a Green economiser, by a Brotherhood three-cylinder hydraulic engine. The pressure is maintained in the mains by two accumulators, with rams 18in. diameter and 20ft. stroke, loaded to a pressure of 75lb, per square inch.
These works have now been in operation for three years, and are supplying a large amount of hydraulic power for various purposes, with the most economical and satisfactory results, and the number of consumers is constantly increasing. About two hundred machines are at present being worked from the high-pressure mains, including lifts and jigger hoists in warehouses for the expeditious storage and delivery of goods, passenger lifts in hotels and office buildings, presses, motors, etc. The cost of lifting by this power is, in some cases, as low as one farthing per ton, lifted 50ft. high. The pressure water is charged for on a sliding scale, and is registered by meters fixed on the exhaust pipes of the machines, from which the water is allowed to run to waste. The power is available day and night, and on Sundays, if required.
THIS cooperage, belonging to Messrs. John G. Whyte and Co., and situated in Watkinson Street, Queen's Dock, is employed exclusively in the manufacture of palm-oil casks by machinery supplied by Dunbar's Cask Machinery Co. The staves are taken in the rough, and passed successively through a dresser, side and end cutters, and a jointer. The cask is then raised, heated, trussed, and worked off ready for heads, which are also made throughout by machinery. The special feature of the works is that the whole process is conducted without the assistance of coopers.
This mill, belonging to Messrs. Earles and King, was established in Oil Street in 1804. The ground then occupied being required for the extension of the London and North Western Railway Goods Station, the present mill was built in 1872 at 65, Burlington Street, with all modern improvements. The principal industry is the crushing of linseed, the extraction of oil therefrom, and the manufacture of linseed cakes. Seven hundred tons of linseed can here be crushed each week, producing about 460 tons of cake and 340 tons of oil. As the oil is used chiefly for painting, about one third of the quantity made is boiled, so as to promote its drying qualities. For this purpose there are two boiling pans, each capable of holding eight tons of oil; and as about ten hours are required to complete the process of boiling, fresh lots of oil can be boiled day and night.
For the pressing of the seed into cake there are twenty-eight hydraulic presses, the larger of which can exert a pressure of 400 tons. The seed is first crushed between chilled-iron rollers, and then heated, or cooked in steam kettles, after which it is placed between woollen wrappers and taken to the hydraulic presses. Here the greater part of the oil is extracted, and the residue is the cake. On coming out of the presses the edges of the cake are soft and oily, and are pared off by mechanical paring tables in order to render the cakes marketable.
They are then cooled in racks, after which they are ready for the market. A compound feeding cake, used largely, and with great advantage, for milch cows, is also made here from different suitable ingredients. The firm have their own cooperage, joiners', and pattern shop; fitting shop, where they make their own machinery' and saddlers shop, where their own belting is made, and harness for the horses. The underground fireproof vaults are capable of holding upwards of 40,000 bags of linseed. The mill itself is also fireproof, being arched above and below.
These are the oldest rice mills in England, having been erected over a hundred years ago for the manufacture of Carolina rice. After the American war the Carolina supply ceased, and was replaced by Burma and India rice, with increased trade.
These mills can treat about 800 tons of rice and grind 180 tons of rice flour per week. The flour machinery, which requires about 120 horse power to drive it, is driven through a friction clutch, so that it can be thrown in or out of gear while the engine is running. The engine is horizontal tandem compound, indicating 450 horse power, and drives the mill from a fly-wheel 20ft. diameter, by means of sixteen cotton ropes.
Steam is supplied at a pressure of 100lb. per square inch from three boilers, all fitted with Bennis mechanical stokers, which effect great economy in fuel and are successful in preventing smoke. Mr. Frederick Dresser's cement for artificial millstones can be seen in preparation and at work.
During recent years large rice cleaning mills have been erected in Burma and India, and now the cleaning of rice in England is rapidly becoming extinct, as rice can be cleaned cheaper abroad. These mills will soon be closed and reconstructed for other business.
These works, belonging to Messrs. R. and J. Evans and Co., are situated at Brunswick Graving Dock; and the machinery and appliances here employed are such as are generally used in iron shipbuilding yards.
These engineering works, the property of Messrs. Fawcett, Preston and Company, are the oldest in Liverpool, having been established in 1775.
At first they occupied merely a small space at the corner of York Street and Lydia Ann Street but they have been gradually extended from time to time until they now occupy the entire area enclosed by four streets. To increase their capacity for turning out work and to economise labour, extensive alterations have lately been made in the buildings and machinery of the works at York Street, especially in the erecting shops and iron foundry.
Mr. Fawcett, who was among the first to apply steam to the propulsion of vessels, built the engines of the Etna, which began to ply on the Mersey in 1817; and in 1840 the firm made the machinery of the President, the largest Atlantic steamer built up to that time.
Between 1817 and 1840 they supplied to the home and foreign government, and to the leading steamship companies, over 170 sets of marine engines of varying powers, up to 540 horse power nominal which was the power of the President. Hall's surface condenser, the first ever applied to marine engines, was here fitted to the Windermere, in 1835.
Since the beginning of this century the firm have also been makers of all kinds of machinery for the manufacture of sugar from the cane, and have recently introduced many improvements in the design of cane-crushing mills, multiple-effect vacuum apparatus for evaporating the water from the cane juice, and stills for making rum from the molasses; examples of each can be seen in various stages of manufacture.
Their system of multiple-effect evaporation has been applied successfully to the economical distillation of fresh water from sea water; and in 1886 two plants were made by them and erected at Suakim to the order of the Government, for the supply of drinking water to the English troops, each plant being capable of producing about 48,000 gallons per day.
The same system has been largely applied to the evaporation of water from alkaline and other solutions and several sets of apparatus for the recovery of soda ash from the spent liquors used in paper works in England and Ireland will be seen in course of construction. For some years past these works have also been noted for the construction of machinery for the manufacture of nitrate of soda; and several of the best appointed nitrate works in Chili are fitted with machinery which was designed and manufactured here.
The Cyclone press of Mr. James Watson is also manufactured here and three of the largest presses ever made, weighing about 95 tons each, have been constructed and shipped this year to India and China, with their complete sets of pumps and engines, for pressing jute, cotton, silk, feathers, &c. One of these presses, now at work in India, of which a working model can be seen in action, has made over sixty bales an hour. A plantation press on a new plan is also in course of construction.
The manufacture of steam boilers and copper work, forming an important branch of the business, is carried on at the Lightbody Street works, which are of modern construction, and are fitted with powerful tools and special appliances.
These works were established in 1850 for the manufacture of locomotives, and stationary and marine work; lately there have been added a shipping yard and forge. They belong to Messrs. John Jones and Sons, who are the only firm in Liverpool conducting in their own premises shipbuilding, engineering, forge, and foundry work.
In 1853 they fitted out some of the first stern-wheel steamers built in this country, shipped them in parts to India, and there put them together on the rivers, as well as light-draught paddle steamers.
In 1857 the Iron Duke, a large paddle steamer of the City of Dublin Steam Packet Company, was cut in two and lengthened 40ft., being the first iron steamer lengthened in this country; she was afterwards fitted with new boilers, and still continues to perform her work in the most satisfactory manner.
In 1878 the extremely full modelled ships for cargo purposes were here introduced, of which the Behan was the pioneer; this has now become the accepted type for cargo steamers. During the last few years steamers of every description have been built and engined by this firm; and a large set of tri-compound engines are now being completed for a screw steamer of 7,000 tons burden, the boilers of which weigh 70 tons each, and are constructed for a working pressure of 180lb. per square inch. Rotary engines have also been applied satisfactorily, in cases where the consumption of steam was not of primary importance.
These works were established in 1824 for the manufacture of forgings of the largest size then required. For many years the hammers were of the belly-helve description; but these have now been all superseded by steam hammers. These works were amongst the first to lay down plant for the manufacture of Bessemer steel and armour plates, but these branches, not proving remunerative, were afterwards abandoned and the machinery dismantled. At present they are engaged exclusively on the manufacture and finishing of forgings in iron and Siemens steel, especially crankshafts, line shafts, and stern and rudder frames for steamers up to the largest class. Here were constructed the stern frames of the City of Rome, La Champagne, and La Bourgogne, and the crankshafts of the Servia and Normandie.
The forge comprises one 12-ton, four 7-ton, one 5-ton, and several smaller steam hammers; and the machine shop is supplied with lathes, slotting and planing machines, of the largest and most powerful description. Here is made a special brand of iron prepared from cold- blast and all-mine pig-irons, for the construction of forgings of the largest size, where reliability and moderate cost are desired. This material recommends itself for crank and propeller shafts of ocean steamers, and for all forgings for land engines, owing to its great power to resist torsional strains; specimens 2ft. long and 2 square inches area rarely fracture until twisted between five and six complete turns, the fracture being always fibrous.
These works, belonging to Messrs. Francis Morton and Co., are situated on the Mersey at Garston, near Liverpool, and cover more than ten acres, comprising a large range of lofty and well lighted buildings for the manufacture of all kinds of constructional ironwork, with private dock and railway siding accommodation.
For over forty years the firm has been engaged in the manufacture of iron roofing and fencing, of iron and steel telegraph poles, of which large quantities have been supplied to the Indian and other governments, and of iron and steel girders. The whole of the wrought-iron main girders, 6.25 miles in length and about 5,000 tons in weight, for the Liverpool Overhead Railway now in course of erection, are being made here, and some 1,600 tons of castings; also the steel swing bridge for carrying this railway across the entrance to the Stanley Dock has recently been completed and delivered.
THESE works, belonging to Messrs. David Rollo and Sons, are employed in the construction of marine engines and boilers, and in the repairing of engines, boilers, and ships.
The machine, fitting, finishing, and erecting shops are situated in Blackstone and Fulton Streets and the boiler and pattern shops, coppersmiths and whitesmiths' shops, iron and brass foundry, forge and smithy, are at Sandhills, and are lighted by electricity. Among the special appliances are one 140-ton hydraulic riveting machine and another of 40 tons; a machine with five drilling heads for drilling boiler shells and ends in place; a machine for flanging furnace fronts, and another for drilling them; a flanging hammer, and three drop hammers for hot stamped work.
These works, the property of Messrs. John H. Wilson and Co., are situated near Sandon Dock, and adjacent to the Sandhills Station of the Lancashire and Yorkshire Railway. They are employed in the manufacture of steam winches and cranes, steam crane excavators, and concrete-mixing machines, which have been extensively used in the construction of the Manchester Ship Canal.
A 10-ton steam crane, fitted with a digging bucket having a capacity of 12 cubic yards, will excavate and deliver into wagons from 800 to 1,000 cubic yards per day of ten hours, according to the nature of the ground; it will work a clear 22ft. face, and drive a gullet 50ft. wide. It has no limit in revolving, and therefore does not require any trimming of the bottom sides of the cutting in order to get wagon roadways in. The concrete-mixing machines, designed by Messrs. Carey and Latham, are made in various sizes capable of turning out from 10 to 70 cubic yards of concrete per hour. They both measure and mix the materials mechanically, and do their work effectively and rapidly.
These works belong to Messrs. Laird Brothers, whose firm was founded in 1824 by William Laird, the father of the late John Laird, M.P.; and since that date there have been built here, including work now in hand, 589 vessels, having an aggregate tonnage of over 380,000 tons, and an aggregate of over 352,000 indicated horse-power.
A large portion of this work has been done for the British and foreign and colonial governments. Many famous and successful vessels of the mercantile marine have likewise been constructed here. Special attention has been given to the design and construction of steamers for river navigation, some of which have been pioneers in opening up rivers that now form important channels of commerce among these steamers is included the John Randolph, the first iron steamer ever seen on American waters. Among the notable ships recently turned out are the twin-screw Atlantic liner Columbia, built for the Hamburg American Steam Packet Co., one of the fastest and most successful ships in the Atlantic trade and the Chilian torpedo gunboats, Almirante Lynch and Almirante Condell, which have recently distinguished themselves im several naval engagements on the coast, notably that which resulted in the sinking of the ironclad Blanco Encalada.
Entering the works from the office, the model room A is on the right; B is the large engine-shop, with a variety of work; and at C are shipbuilding tools, and a frame-bending furnace.
The two southernmost slips D and E are prepared for laying down H.M. ships Onyx and Renard, twin-screw torpedo gunboats of 735 tons displacement and 3,500 I.H.P.
At F the route lies past No. 5 graving dock, and on board H.M. first-class twin-screw battleship Royal Oak, length 375ft. by 75ft. beam and 44ft. depth; displacement 14,300 tons, 13,000 I.H.P. Between Nos. 4 and 5 docks is a new shop fitted up with shipbuilding machinery specially adapted for the heavy work on this vessel.
At G in No. 4 graving and fitting dock lies, nearly ready for sea, the Ibex, a steel twin-screw fast channel steamer for the Great Western Railway, 265ft. by 32.5ft. by 15.5ft., 4,000 I.H.P., speed 19 knots.
In the engine erecting shop are in course of erection the engines for the Royal Oak, of 13,000 I.H.P.; also twin-screw engines of 4,000 I.H.P. for steamship 582, and screw engines of 3,000 I.H.P. for steamship 583.
On No. 2 slip I is No. 584, a steel twin-screw passenger steamer for the Brazilian coasting trade, 220ft. by 30ft. by 12ft., 900 tons, 650 I.H.P.
On No. 1 slip K is No. 582, a twin-screw mail and passenger steamer for the Fleetwood and Belfast service of the Lancashire and Yorkshire and London and North-Western Railways, 311.5ft. by 36ft. by 15.75ft., 2,000 tons, 4,000 I.H.P. At L is shipbuilding machinery.
At M is No. 3 dock under a permanent roof, in which is building a screw steamer, No. 583, for the Atlantic cattle trade, 403ft. by 45ift., 5,000 tons, 3,000 I.H.P. At N is the smithy.
At the north end of the works are the steam sawmills 0, and the joiners' shops P, with mould loft, &c.
The boiler shop is situated in Beaufort Road, and opposite is Gilbrook yard, where are the 9 de Julio and Independencia, river ironclads for the Argentine Government, 240ft. by 44ft. by 22ft., carrying two 24-centimetre guns in barbettes, four 41-centimetre guns, and four 3-pounder quick-firing guns. The boiler factory was completed in September, 1888, and has already turned out a large number of boilers, many of which are of exceptional size, some of them having weighed 75 tons each. The ground covered by buildings is nearly 6,000 square yards.
The factory consists of four principal spans, parallel to one another, the largest of which is reserved for the erecting work; it is 236ft. long by 53ft. wide and 58ft. high. The annexe on the east is the shop for receiving and preparing the material ready for erecting. Another annexe on the west is devoted to the lighter work, and still farther to the west is the smiths' shop. The factory is supplied with the most modern machinery, and with travelling cranes driven by power; it is adapted for the highest and largest class of high-pressure marine boilers. The offices for managers and foremen are near the entrance, and over these are a large drawing office and a mould loft.
These works, belonging to Messrs. Clay, Inman, and Co., were erected twenty-two years ago for the manufacture of wrought-iron and steel forgings of the largest description, including stern frames and rudders. They are situated close to the graving dock and other docks in Birkenhead, with railway communication into the premises. The furnaces are worked throughout on the Siemens regenerative gas system, and the cranes by hydraulic power. There is also a turning shop, containing very powerful lathes and other machinery.
This vessel, and her sister ship the City of New York, are the largest passenger steamers in the world. They were built by Messrs. James and George Thomson, Clydebank, for the Inman and International Steamship Co., and their principal dimensions are: Length on water-line, 525ft.; length over all, 560ft.; breadth, 63ift.; depth moulded, 42ft.; gross tonnage, 10,508 tons. They are built of Siemens-Martin steel from the works of the Steel Co. of Scotland and the Mossend Steel Co.
The hulls are divided by transverse bulkheads into fifteen watertight compartments, including three for boilers and two for machinery, the latter being further divided in each case by longitudinal bulkheads, rendering the vessels practically unsinkable. None of the compartments exceed 35ft. in length, and the quantity of water they would hold would be 1,250 tons to load water-line, or 2,250 tons to upper deck. Even were two or three compartments filled, the flotation of the vessels would not be placed in danger, and their buoyancy could easily be trimmed. The vessels have double bottoms, the inner one being over four feet above the outer; and have special rudders, formed so as to be a continuation of the lines of the vessels below the water-line. The rudder was designed primarily for use in warships; and these vessels have been specially retained by the Government as armed cruisers in the event of war. They are driven by twin screws worked by separate sets of machinery, and are the first high-speed Atlantic liners so propelled. The engines are placed in two compartments, separated by a longitudinal water-tight bulkhead while transverse bulkheads on each side isolate them from other parts of the vessel. There are two sets of triple-expansion engines, each with cylinder, of 45in., 71in., and 113in. diameter, with 5f t. stroke, their total indicated horse power being 18,000. There are nine double-ended steel boilers, with six furnaces in each the working pressure is 150lb. per square inch, and the total heating surface is 50,040 square feet.
The passenger accommodation includes handsome dining-saloons, drawing-rooms, well-furnished libraries, smoking-rooms for first and second class passengers, and barbers' shops. The vessels are fitted throughout with electric light, and possess every modern improvement that has been devised for the safety and comfort of passengers. The accommodation for steerage passengers is also of the best description. The City of Paris made the passage westward in 5 days 19 hours 18 minutes in August, 1889; and eastward in 5 days 22 hours 50 minutes in December, 1889, which are among the fastest passages ever made.
These works, belonging to Messrs. Lever Brothers, occupy an area of 52 acres on the Bromborough Pool, opening into the Mersey above Birkenhead, and are in direct communication with the Chester and Birkenhead Railway. The main buildings cover an area of nearly four acres, and comprise the following: soapery, frame-room, drying-room, stamping-room, offices, dining-rooms, engine-house, boiler- shed, mechanics' and joiners' shops, electric-light room, box-making rooms, railway shed, and loading stage.
The soapery is a fireproof building three storeys high, and is capable of turning out 750 tons of soap per week. At one angle of this building a tower 20ft. square and 90ft. high supports a water tank for supplying water to the sprinklers for extinguishing a fire. The boiling rooms are situated on the top floor of the soapery, where there are placed twenty-four boiling pans, each with a capacity of 60 tons of liquid soap.
The fat and other raw materials are brought to the works in casks, in which they are melted by a steam jet, and are afterwards pumped up into the boiling pans. When this boiling has completed the saponification or proper blending of the alkalis and acids, so as to avoid the presence of free or un-neutralised alkalis in the soap, which usually occupies at least ten days, the soap is allowed to stand for a time, in order that any slight sediment may settle; and then the layer of clear soap remaining above is run off through wooden spouts into frames, where it is allowed to cool, and is then removed for cutting into slabs and bars.
The pieces of soap are next taken to the stamping machines, of which there are sixty, some worked by steam and some by hand; here they are stamped into lettered tablets, after which they are wrapped up and packed into card boxes and wooden cases for transit.
In the box-making department are sawing, printing, nailing, and other machines for the manufacture of boxes and cases. The wood for the cases is first sawn up, then printed, and lastly passed through the nailing machines, which fasten the parts of the case together. There are eleven of these nailing machines, capable of turning out over 8,000 cases per day. From 350 to 400 girls are employed in the manufacture of card boxes, which are all made by hand.
The total number of persons employed in these works is over a thousand. All the ingredients used in the manufacture of the soap are analysed in the laboratory before being used samples are also taken during the process of manufacture and analysed; and finally, portions are taken from each batch of finished soap and subjected to a third examination, to ensure no deleterious substances remaining in the soap.
The Horwich Works, of which the building was commenced in 1886, have been erected for the purpose of repairing and renewing the locomotive stock, and of carrying out the mechanical engineering work of the railway.
They are situated between the Chorley New Road, Horwich, and Red Moss and are about one mile distant in an easterly direction from Blackrod Station upon the main line between Manchester and Fleetwood. The land enclosed for the works comprises 85 acres, and lies north-west and south-east. The covered area of workshops is 15 acres. They comprise offices, general stores with gallery, boiler shops, smithy, forge, foundries, tin and copper shops, machine shops, erecting and repairing shops, &c.
For the carriage of materials from the stores and of work to the several shops, five miles of tramways of 18in gauge have been laid throughout the works, the haulage being performed by small locomotives. The cylinders are 5in. diameter, with 6in. stroke, and 2ft. 3.25in. centre to centre. The wheels are 16.25in. diameter, the frames 7ft. 4.25in. long, and the extreme width of the engines is 3ft. The boilers are of steel, 2ft. 3in. outside diameter, 2ft. long between tube plates, and work at a pressure of 170lb. per square inch. The tractive power of the engines is about 1,4001b., and their weight when full and in working order 3.19 tons.
The rolling stock includes locomotive boiler trolleys, and several kinds of trucks, all built of iron throughout. The locomotive boiler trolley consists of a pair of four-wheeled bogies connected together by a wrought-iron bar, and fitted with special arrangements for supporting the boiler. Some of the trucks have flat tops, others have deep sides, and a third class have still deeper sides and are mounted as tip trucks.
THE total length of the canal is 35.5 miles, from the docks in Manchester down to the entrance locks at Eastham on the tideway of the Mersey, six miles above Liverpool. The total fall of water level is 60.5ft., which is divided among four sets of locks.
The first set of locks is at Mode Wheel, 1.75 miles from the terminus of the Manchester docks, and the fall here is 13ft.; the second is at Barton, 3.25 miles further, with 15ft. fall; the third is at Irlam, 2 miles below Barton, with 16ft. fall ; the fourth at Latchford, 7.5 miles below Irlam, with 16.5ft. fall.
This upper portion of the canal, 14.5 miles from Manchester to Latchford, will be filled with the waters of the Irwell, Hersey, and other rivers; it will, in fact, be a canalised river, taking the place of the Irwell and Mersey through this distance, and continuing to be, as these rivers are at present, the main drain for their watersheds in Lancashire and Cheshire. Large sluices are therefore being provided at each set of locks, for the passage of land floods and surplus water.
Of the 21 miles forming the lower or tidal portion of the canal from Latchford to Eastham, the twelve miles from Latchford to Runcorn are inland the remaining nine from Runcorn to Eastham follow the south-western shore of the Mersey estuary; the route lying mostly inland, but partly on the foreshore where necessary to cross sinuosities in the bank for obtaining a more direct course for navigation. Throughout this tidal length the water level will be maintained at about mean high water at Eastham, namely, 14ft. 2in. above the Old Dock sill at Liverpool.
The entrance locks at Eastham are being constructed for admitting vessels at almost any state of the tide; their lower sills are 3ft. deeper than the entrance channel, which is being dredged deep enough to give 30ft. at high-water neap tides and 4Oft. on spring tides, so as to enable large vessels to navigate the entrance during a great part of every tide, and others during almost the whole time.
There are three locks alongside of one another, the largest being 600ft. long by 80ft. wide, the next 350ft. by 50ft., and the smallest 150ft. by 30ft. There are also two sluices, each 20ft. wide, for assisting in filling the canal; besides which, on all tides above the ordinary level of the water in the canal, all the lock gates will be opened as soon as ever the tide rises to that level, and will be kept open till high water. Spring tides will rise from 5ft. to 7ft. above the ordinary water level in the canal.
The four sets of locks for the upper reaches of the canal will each consist of two; a larger lock 600ft. long by 65ft. wide, and a smaller 350ft. by 45ft. The minimum depth of the canal will be 26ft and the lock sills are being constructed 2ft. deeper, in view of future deepening of the canal by dredging. All the lock gates are constructed of hard Demerara green-heart, which has been found to be exceedingly durable, and the wooden gates are less liable to damage than those made of iron. The gates will be worked by hydraulic power at each lock, the engines and machinery being constructed by Sir W. G. Armstrong, Mitchell, and Co.
In the two reaches of five miles from Manchester down to Barton the canal will be 230ft. wide at water level and 170ft. at bottom. Throughout the rest of the 30.5 miles from Barton to Eastham the width of water level will average 172ft., with a minimum of 120ft. at bottom. The width will allow of large steamers passing each other at any part of the canal. At the several locks it is widened out considerably, and will admit of vessels turning if necessary. At manufacturing works built on the sides of the canal it will be widened out for allowing vessels to lie alongside wharves without interfering with the regular traffic up and down.
On the nine miles length along the foreshore from Runcorn to Eastham embankments have to be formed; where these are on sand, close piling is driven at the foot of each bank; where the foundation is rock or clay, they are made of clay hearting protected by heavy stonework. They are generally 30ft. wide at top, with outside slopes of 11 to 1, and in slopes of 1 to 1. In these embankments will be constructed three weirs, each 600ft. long, for allowing the tide when above ordinary water level to flow into and out of the lower portion of the canal.
In the embankment opposite the river Weaver are ten large sluices, each 30ft. wide, for allowing the Weaver water to flow out of the canal, and also for tidal flow. They are on Mr. Stoney's plan, working on a movable frame of rollers; being balanced, they work with great ease, requiring only slight power to lift them. Similar sluices are provided for letting off flood and surplus water from the upper reaches of the canal; there will be four alongside the locks at Mode Wheel, four at Barton, five at Irlam; but only three at Latchford, because the Mersey flood water will flow down the river channel as at present from the point where the canal leaves the river, a little above Latchford.
The docks at Manchester will have a water area of 114 acres, and a quay area of 152 acres; and the length of the quays will be 5.25 miles. At Warrington a dock is proposed with a water area of 23 acres. At Partington the canal is widened to allow steamers to lie on either side. The Weaver embankment will pen the water three miles up that river to Frodsham, rendering an extensive sheet of water available for vessels of any size after it has been dredged deep enough. The large dock thus formed is joined to the Weaver navigation by a lock 229ft. long and 42ft. wide, which will admit the Cheshire salt traffic to the canal.
Large locks are being built in the embankments at Weston Point and Runcorn, for allowing coasters and barges to enter and leave the canal from and to the docks at these places. The shipping at Ellesmere Port will use the locks at Eastham. At Old Randles, above Runcorn, two sluices, each 30ft. wide, will enable tidal or river water to be let into or out of the canal.
Where railway lines cross the canal, they are being raised by high-level deviations extending 1 miles on each side of the canal, so as to allow a minimum headway of 75ft. the full navigable width of 120ft. will also be maintained under the bridges. As the railway viaducts are mostly on the skew, the clear spans of their openings vary from 137ft. to 266ft.
Between Barton and Runcorn are two high-level road bridges, and six swing road bridges; the latter will be worked by hydraulic power, as will also the movable aqueduct for carrying the Bridgewater Canal over the Ship Canal. The aqueduct will consist of a long iron caisson, turning like a swing bridge upon a central pier, with an opening of 90ft. width on each side. The water will be retained in the caisson while swinging round, and also in the Bridgewater canal, by lifting gates at each end.
The Ship Canal passes through either red sandstone rock or marl, overlain by alluvial deposits of clay, gravel, sand, or loam. The rock is used for pitching the slopes where the soil is soft and requires protection from the wash of the steamers. The gravel and sand are used for concrete, of which 1.15 million cubic yards are required. Concrete is used wherever practicable in dock and lock walls. The copings and hollow quoins are of Cornish granite hard sandstone and limestone are used for other portions.
The total amount of brickwork, which is all faced with blue bricks, is 175,000 cubic yards, requiring nearly 70 million bricks and there will be 220,000 cubic yards of masonry. The lower portions of the dock and lock walls are formed of concrete, which is protected at the water level by granite or limestone fender courses projecting slightly from the face of the wall. Above these courses the concrete walls are lined with brickwork. In the upper portions of the dock walls are built culverts for hydraulic and gas mains.
The deepest cutting is 66ft. deep, for a short distance near Runcorn. The largest cutting averages 55ft. deep for a length of 1 miles near Latchford. The slopes of the cuttings vary between 1 to 1 and 2 to 1, except in the rock cuttings, where the sides are nearly vertical. The total amount of excavation in the canal and docks amounts to about 46 million cubic yards, of which 10 million is in sandstone rock. The spoil is used for filling up river bends which are cut off by the canal, and for raising adjacent low-lying lands.
Lake Vyrnwy, the new source of water supply for Liverpool, is situated in Montgomeryshire, North Wales, 10 to 15 miles from Bala station, and 9.5 to 14.5 miles from Llanfyllin station. The lake has been formed by building a masonry dam across the valley of the river Vyruwy, a tributary of the Severn, near its narrowest part.
The site was not chosen for this reason alone, but also because the rock appearing here in the bottom of the valley was found to have formed in past ages the natural bar or dam of a post-glacial lake, subsequently filled up by the alluvial deposit brought down by the streams above. A trench 1,100ft. long, 120ft wide, and 60ft. below the alluvial surface at the deepest place, was made right across the valley down to the rock forming the ancient natural bar. All the loose silt, gravel, and boulders were removed, and the sloping rock was stepped so as to form a secure foundation for the base of the masonry dam; and the river Vyrnwy, which flowed through the valley, was diverted and carried over the excavation.
When the lake is full to the overflow, the surface is 825ft. above sea level, and the principal dimensions are: superficial area, 1,121 acres ; length, 4.75 miles; average width, 0.5 mile; maximum depth, 84ft.; capacity, 13,125 million gallons. The area of the present gathering ground is 18,000 acres, which the Corporation have power to increase to 23,200 acres, by diverting two other streams. It is estimated that the rainfall will then yield an average daily supply of at least 53 million gallons, of which 40 million gallons will be available for Liverpool after delivering the required compensation water to the river below the dam. The length of the road round the margin of the lake is nearly 12 miles, including the road over the dam.
Masonry Dam. The dimensions of the dam are as follow: Total length along carriage way, 1,165ft., or 0.22 mile ; height of parapet above bottom of foundation, 161ft.; height from river bed to sill of overflow, 84ft.; greatest head of water at base of dam, 146ft.; greatest thickness at base, 120ft.; width of roadway between parapets, 19.8ft.; batter of wall, inside 1 horizontal in 7.25 vertical, outside 1 horizontal in 1.5 vertical; total quantity of masonry 260,975 cubic yards, or 510,000 tons.
The dam is built of hard dark grey stone, commonly known as "clay slate," from the lower silurian formation, obtained from a quarry situated about 1.25 mile north, up the valley of the Cynon stream. The masonry is coarse rubble; some of the stones weighed as much as ten tons, and more than one-third of them weighed over four tons. The roadway over the dam is carried on 31 elliptical arches of 24ft. span. The carriage way is 14ft. above the top of the darn, which itself forms the sill of the overflow from the lake; the surplus water flows through the central nineteen arches of the roadway, and down the outer slope of the dam.
Compensation Water. The daily compensation water to the river is discharged through an 18in. pipe, laid in an outlet tunnel through the dam at the natural ground level. A continuous daily supply of ten million gallons is discharged in this way. Every year also, at times appointed by the Severn Commission, 12,000 million gallons have to be delivered into the river in the form of freshets, each of forty million gallons per day for four days, which are discharged through a 30in. pipe laid alongside the 18in. pipe. The compensation water is measured in a building near the discharge pipes. The exact size of the orifice by which the flow is measured was determined by a permanent gauging basin, which may be used at any time.
Vyrnwy Tower. The entrance to the Liverpool aqueduct is about three-quarters of a mile from the dam in 50ft. depth of water. The tower containing it stands 104ft. above the surface of the lake, and is approached from the road by a causeway carried on four arches. Its internal diameter is 30.5ft. The valves by which the water is drawn in from the lake are of novel construction. Within and without the tower are two stand pipes, connected at the bottom beneath the foundation of the tower. Each length of pipe forming either standpipe has gunmetal faces, and is not connected with its neighbours above or below. By hydraulic pressure those above any joint may be lifted. The water flows through the annular space, and may thus always be drawn through the joint nearest to the surface of the outside water, and discharged through that nearest to the surface of the inside water. By this means the best water is obtained, and the water about the strainers is not disturbed.
Inside the tower the water is strained through screens of fine copper-wire gauze, to cleanse it from impurities held in suspension. When a screen gets clogged it is raised by hydraulic pressure, and automatically cleansed by jets of water from a peculiarly-constructed turbine. An automatic signal bell gives notice when a screen gets clogged. The hydraulic machinery in the straining tower is worked by pumps, driven by water from a small reservoir on the adjoining hillside.
Aqueduct. The distance along the aqueduct from the lake to the Town Hall, Liverpool, is 76 miles. It consists for the most part of cast-iron socket pipes, varying from 39in. to 42.5in. inside diameter, and from 1in. to 2.25in. thick. The pipes are made in 12ft. lengths, and are jointed with lead. For about four miles the water flows through three tunnels and in some specially important places, such as river crossings, through mild-steel pipes.
This tower carries the last of five balancing reservoirs on the aqueduct between Lake Vyrnwy and the old Prescot reservoirs, eight miles from Liverpool. It is situated at Norton, near Runcorn, about 17 miles along the aqueduct from Liverpool. As the ground is here more than 100ft. below the hydraulic gradient, a tower had to be constructed for raising the tank to the required level.
The structure is of Roman Doric design, built of the new red sandstone of the district its height to the top of the tank is 113ft., and its diameter at the base is 95ft. The tank is supported without girders or columns; cast-iron bed plates resting upon the circular cornice of the masonry support by means of a hard steel expansion joint a hoop of riveted steel plates of the same diameter as the tower, designed to resist compression towards its centre. The bottom of the tank is constructed entirely of mild-steel plates, riveted together in the form of a segment of a sphere the vertical sides are of cast iron. The principle is that of an inverted dome under tension, and no internal supports are required. The capacity of the tank is 651,000 gallons.