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Note: This is a sub-section of 1890 Institution of Mechanical Engineers
Visits to Works (Excursions) to the Sheffield area
THE SHEFFIELD TECHNICAL SCHOOL.
This School, situated in St. George's Square, was erected in 1885 by private subscription. The town of Sheffield however has recently adopted the provisions of the Technical Instruction Act, and the school is now assisted by the rates. Courses of instruction are provided in applied science to both day and evening students, a special feature being made of the subjects of steel and iron manufacture and mechanical engineering. The complete course of study in each department extends over three years.
The metallurgical laboratory is equipped with the most modern apparatus for metallurgical analysis, more especially with appliances for the rapid and accurate chemical examination of iron and steel, fuel, and refractory materials. A small steel works has been erected, including melting-holes, pot-house, malleable-iron furnace, &c. An iron foundry, and a 25-cwt. open-hearth furnace with three systems of gas-producing, are now being built. The instruction is conducted on a thoroughly practical scale, and includes mixing, melting, casting, and chemically and mechanically testing various qualities of steel and iron.
The mechanical engineering department is also equipped with all the necessary appliances for the education of mechanical engineers. The complete course includes attendance at lectures and classes, experimental work in the laboratories, and practical work in the workshops and drawing office. The workshop course, though not intended to supersede the practical training which can be obtained only in the engineering factory or workshop, serves to familiarize students with the construction and use of tools, and with the principles upon which these depend, and with the ordinary workshop operations of mechanical engineering. The experimental work in the laboratory is of a practical and useful kind, affording information which cannot as a rule be obtained in works, for want of opportunity or appliances. The laboratory is fitted with a vertical tubular steel boiler; a compound steam-engine capable of indicating 50 horse-power, and designed to work under a variety of conditions for illustrating steam-engine economy; a 50-ton Buckton testing machine; and a 4-H.P. Stockport gas-engine. The machine shop contains lathes, planing, shaping, slotting, and drilling machines, and all the necessary shop and bench tools. The wood-work shop contains benches to accommodate twenty-four students working at one time, and six wood-turning lathes driven by steam power. The smith's shop contains appliances for giving instruction in forging, welding, hardening, tempering, &c. The drawing office is one of the largest and best equipped in the country. Several other branches of instruction are provided for evening students.
NURSERY WIRE MILLS.
These works, situated in Nursery Street, are the property of Messrs. Cocker Brothers, who, as manufacturers of crucible-steel wire since 1752, confine themselves now to the highest classes of wire, of which the following four descriptions are made:—first, for lace needles and stocking-loom needles; second, for hand-sewing and sewing-machine needles; third, for watch and clock parts; fourth, for all kinds of spiral-coil springs. From the last is made every kind of spiral springs suitable for colliery and engineering purposes; a colliery-cage bumper-spring has been tested at local collieries with excellent results. All kinds of drawbar and valve springs are also made; and Ramsbottom piston-rings for steam-hammers and small locomotives. A special wire for making small pinions is also drawn in sizes varying from half an inch down to one-sixteenth of an inch diameter. It is deeply grooved, so as to form from six to twelve ribs or leaves upon it; and when it is cut up into short lengths, the leaves form the teeth of the pinions.
FITZALAN STEEL WORKS.
These works, formerly belonging to Messrs. Marriott and Atkinson, and now to Messrs. Cocker Brothers, extend over an area of four acres in Effingham Road, Attercliffe; and comprise steel-melting furnaces, forge, rolling mills, and file-making machinery. The newest machinery has recently been put down for manufacturing road-van and carriage springs and axles.
In the file department are nine file-cutting machines by Mr. Ambrose Shardlow of Sheffield; a considerable number of files are also cut by hand. A file-grinding machine by Mr. David Ashton of Sheffield, capable of grinding forty dozen blanks per day, consists of a large revolving gritstone carried on a horizontal spindle which has a longitudinal reciprocating traverse imparted to it by means of a cam. The blanks to be ground are placed in a rest, which holds from eighteen to twenty-five at a time; in this they are fed under the stone and withdrawn again, by means of a screw attached to the rest; the screw is actuated by fast and loose pulleys with crossed and open belts.
In the carriage-spring department are forging machines of various kinds, one of which forms at a single blow the two bosses on the ends of the springs. Carriage axles are made from scrap, forged in dies under a steam hammer in a single heat.
A specialty made at these works is a railway-wagon card and ticket fastener, adopted on several of the leading railways, to which over half a million have already been supplied.
WAVERLEY STEEL AND FILE WORKS.
These works, belonging to Messrs. Dickson Brothers and Co., and adjoining the Attercliffe Road Station of the Midland Railway, are of recent erection, and have been specially laid out for the manufacture of crucible cast-steel and of hand-cut files.
The steel works include the pot house in which the fire-clay steel-melting crucibles are made, the mixing room in which the constituents for the steel are weighed off and mixed for melting, the melting furnace itself, and the steel warehouse in which the finished bars are all thoroughly examined. The most interesting process in the manufacture is the "teeming" or casting of the crucible-steel ingots, which takes place three times a day.
The file works consist of forging shops, annealing room for softening the files, cutting shop, hardening shop, scouring room, warehouse, and packing rooms.
BRIGHTSIDE BOILER AND ENGINE WORKS.
Hawksley, Wild and Co
These works, situated in Savile Street East, were established in 1860 by the present owner, Mr. G. W. Hawksley, and his late partner, Mr. M. Wild. The manufacture comprises boilers of all kinds with the necessary fittings, feed-water heaters, and apparatus for heating large quantities of water for baths, breweries, &c.
The flanged flued boilers here manufactured have the flues built up in rings of plates of alternate larger and smaller diameter, the difference in diameter being about 4 inches; the ends of the smaller rings are expanded out to fit inside the ends of the larger, which are plain cylindrical rings. The circular seams thus made afford great resistance against collapse, and provide amply for free expansion and contraction; at the same time with the addition of cross tubes they ensure a thorough mixture of the gases passing through the flue. Large numbers of boilers fitted with these flues are working with satisfactory results. The rings forming the flues are each made from a single plate, bent into a cylindrical form by horizontal plate-rolls of forged steel, which will bend cold steel plates 10 feet wide and 1 inch thick. The ring when rolled envelopes the top roll; and for enabling the ring to be removed from the rolls, the bearings of the top roll are so arranged that one of them can take the weight of the roll, while the other can be screwed back and swung out of the way, so as to release the ring endways. The rivet holes are drilled in position after the plates have been bent to shape. For the circumferential seams there is a three-standard vertical drilling machine by Messrs. Smith and Coventry of Manchester. For the longitudinal seams another vertical drilling machine is employed, having two saddles on a single standard, and two drill spindles to each saddle; the spindles are adjustable so as to drill two rows of holes at suitable pitch. A machine with several motions has a revolving table enabling a circle of 10 feet diameter to be cut by this motion; it has also a revolving head fitted with a massive steel spindle 8 inches diameter, by means of which a very steady cut of 4 feet diameter can be taken. A new boiler shop in course of erection will contain a flanging press capable of flanging at one operation plates 11 feet diameter. It will have four rams, so as to be suitable for lighter work without loss of power; the two centre rams will work concentrically one within the other, whilst the two others will be placed at the sides, thereby affording a considerable range of power, from the single small ram in the centre to the whole four. The first steel boiler made at the starting of the works about thirty years ago was used here until replaced by a larger, and is still working in Sheffield at a pressure of 80 lbs. per square inch. It is of the flued type, fitted with the flanged rings above described; as each ring is made from a single plate, there is no longitudinal line of rivets exposed to the fire.
The feed-water heater manufactured at these works consists of a horizontal or vertical cylindrical casing containing tubes. Exhaust steam from the engine is admitted to the casing, while the feed-water is pumped through the inside of the tubes, and thence direct to the boiler. The heater is divided in two longitudinally, and the water passes first through the tubes in one half, and then returns through those in the other; the steam travels through the casing in the opposite direction. Tho same kind of heater is constructed for breweries, dye works, and similar purposes. For a dye works a special filtering apparatus has recently been constructed, which is now satisfactorily filtering 40,000 gallons per hour of impure river water.
SILVER AND ELECTRO-PLATE MANUFACTORY.
These works, belonging to Messrs. William Hutton and Sons, were built in 1885, and occupy a rectangular area of three quarters of an acre, having a frontage 230 feet long to West Street. The workshops, show-rooms, and warehouses are arranged round the outside, and the engine and boiler houses, furnaces, and rolling mills occupy a portion of the yard in the centre. Steam is supplied by two steel Lancashire boilers to two Tangye's 25 horse-power horizontal automatic engines placed side by side, each driving a separate portion of the machinery, while either engine with one of the boilers is sufficient to drive the whole of the machinery if necessary. In the furnaces the metals are mixed and melted in crucibles, and subsequently cast into flat ingots of sterling silver or nickel silver as required. In the rolling mill these ingots are rolled down by special rolls into sheets of suitable thickness.
The works are divided into five departments, each under separate management:— spoon and fork, hollow-ware, cutlery, silver, and electro-plating.
In the spoon and fork department, the sheet metal is first cut into narrow strips and short lengths, which are next thinned down at the ends by being passed through special rolls, then annealed, punched into rough form, and finally stamped into proper shape by steel dies, after which they are ready for finishing and plating. In the machine shop the manufacture of these articles is accelerated and improved by the substitution of reciprocating semi-circular steel dies exerting a great pressure, whereby a better finish is obtained with greatly increased rate of production. Two men with one of these machines are able to produce at the rate of eighty dozen spoons or forks per hour.
In the hollow-ware department are made dinner and tea services, and all kinds of dishes, trays, &c. The sheet metal is stamped into shape and embossed by means of steel dies worked by powerful steam-stamps. Raised borders, handles, spouts &c. are hammered from flat metal; and ornamental castings are made in moulds and afterwards chased. These are then soldered to various articles by means of gas blow-pipes. Spinning and turning are also employed for the production of various shapes.
In the cutlery department, one of the processes is close-plating, or the soldering of sheet silver upon the blades of steel fruit or dessert knives and forks. Pearl and ivory cutting and carving are also carried out in connection with the manufacture of fish, fruit, and dessert knives and forks.
In the sterling silver department, a large number of silversmiths are employed, raising, chasing, embossing, engraving, and otherwise ornamenting all kinds of silver plate and other silver articles. Here are also buffing and burnishing shops, and designing and modelling rooms.
In the electro-plating department, the electric current for the plating vats is supplied by two powerful dynamos; and the articles to be plated are kept in motion by machinery, in order to accelerate the deposit upon them of the silver held in solution. Each article is weighed before being put in and after being taken out of the vat, in order to determine the quantity of silver deposited.
HORSE-HAIR CLOTH WORKS.
Samuel Laycock and Sons
In these works, belonging to Messrs. Samuel Laycock and Sons, is conducted every process for the manufacture of horse-hair and hair fabrics. The manufactory, which has been established over a century, is situated in Portobello Place; and from 15 to 20 tons of horse-hair per week are here worked up. The tails and manes are obtained from South America and Siberia, and arrive in a very untidy state, as rough mops of hair, often entangled plentifully with burrs. They have to be carefully washed and combed out, after which the hairs have to be sorted according to their several lengths. The longest hair is 6 feet, but such a length is rare; usually it does not exceed 5 feet. In weaving horse-hair cloth therefore the weft cannot exceed this length; and as the hair is both hard and elastic, and each single hair is considerably thicker at one end than at the other, the construction of a loom for weaving such material with rapidity and success is attended with peculiar difficulties. The warp is of cotton or flax, and is so buried in the hair that it does not show in the woven fabric. Unless the hair is intended to be woven in its natural colours, it is bleached or dyed before weaving, when an artificially coloured fabric is desired.
A large number of old hand-looms are still employed for weaving the horse-hair cloth. These are each worked by two women, one of whom serves or feeds a single hair at a time to the other, who draws it through the open shed. The hairs have to be laid with their thick and thin ends alternating, in order to keep the thickness of the cloth uniform throughout its width. The cloth is woven from 14 inches to 36 inches wide.
To the rest of the interesting machinery in operation in these works has been added an ingenious loom, the invention of Mr. W. S. Laycock, in which the weaving is done altogether automatically. The bundles of hair are placed in two troughs, one on each side of the loom, all the thick ends being arranged to lie together and nearest to the loom. At each side of the loom, close to the trough of hair, is fixed a selecting instrument, from which a selector descends to the bundle of 15,000 to 20,000 hairs, and selects and withdraws a single hair; this is afterwards taken by the shuttle from the selector, and drawn into the open shed of the warp. The operation is repeated with every alternate movement of the shuttle. Should the selector fail to seize a hair on its first descent, it repeats the attempt a second time, and if necessary a third time, before the shuttle has travelled to and from the other side of the loom. If the selector fails in its third attempt to seize a hair, the weft stop-motion is brought into action, and prevents the shed from changing, and stops the let-off of warp and the take-up motion; and the hair selected by the instrument at the opposite side of the loom is then drawn into the open shed, thus preventing any imperfection or fault from the above cause in the hair cloth. Not only has the selector to seize the hair and hold it until it is taken by the shuttle, but it must then also let it go at the right instant: not too soon, or else the hair would be dropped; and not too late, or else the hair would be dragged through the gripping fingers of the selector, and these would soon become worn out. The gripping fingers on the shuttle are also similarly arranged to take hold and let go at the right instant. This self-acting loom is employed for weaving hair blind-cloth, hair seating, and other fabrics made with horse-hair, which are now largely used by the principal railways in this country and on the continent.
Curled hair, used for upholstering seats of railway carriages, steamboats, and domestic furniture, is prepared by carding it after washing, and then spinning it into ropes, so as to give it the curl which affords the springiness necessary to make a comfortable cushion.
RAILWAY-CARRIAGE FITTINGS WORKS.
W. S. Laycock
At these works, belonging to Mr. W. S. Laycock, and situated in Victoria Street, novel machinery is employed for the manufacture of blind rollers and other fittings invented by him for railway carriages and steamships, &c. The blind rollers are so contrived that the blind, made usually of horse-hair cloth, will stay in any position intermediate between top and bottom. Within the hollow brass box at one end of the roller is coiled a spiral spring tending to roll the blind up. At the bottom of the blind is a weight just too heavy for the spring to lift but when the weight is lifted by hand, the blind will roll up. When the weight is unsupported, the blind is prevented from running down by a ratchet and paul in the brass box at the other end of the roller. The ratchet is connected with the roller by a pair of friction discs pressed together by a spring; a slight pull by the hand is sufficient to overcome the friction of the discs, and to draw the blind down. It is then retained in any position by the weight, which is not heavy enough to make the friction discs slip; while the spring tending to pull the blind lip is not strong enough to overcome the weight. The device is simple, and little likely to get out of order.
A double-cone ventilator for railway carriages is constructed of two hollow cones, laid horizontally in the same straight line, base to base, with a space between; the space is surrounded at a short distance by a flat ring, which also covers a short length of the cones. There is thus an annular space between the bases of the cones, and an external annular space between these and the outside ring surrounding them. A short open pipe from the roof of the carriage communicates with the interior of the cones. The horizontal axis of the cones being placed transversely to the direction of motion, the air on striking their surfaces is deflected laterally towards the apex on each side, thereby producing a partial vacuum underneath the flat ring, and thus inducing a suction from the carriage through the short pipe into the interior of the cones. When this pipe is 4 inches diameter, it is found that at a speed of 60 miles an hour a light diaphragm placed across its mouth will support a weight of 2.5 ounces.
Among the numerous other articles produced at these works are lubricators for axle journals, spring seats, window lifts, and draught excluders. The machinery employed in the manufacture is driven by a gas engine, and the electric lighting apparatus by another of a different kind.
ROYAL CUTLERY AND SILVER-PLATE WORKS.
Mappin and Webb
These works, belonging to Messrs. Mappin and Webb, are centrally situated in Norfolk Street, and include an extensive range of melting furnaces, rolling mills, hammer shops, steam-stamp shops, grinding wheels, forging hearths, and silversmiths', cutlers', engraving, chasing, and fluting shops; also cutting out, buffing, finishing, spinning, and turning machinery shops. The whole are systematically arranged, so that the production of every article can be traced from the first stage to the last. In the plating room are some of the largest cast-iron vats ever constructed, containing silver and gold solutions; and the process of electrical deposition, with its numerous appliances and intricate machinery, can here be seen throughout its whole extent.
These works, situated in Blonk Street, were established by Mr. Thomas Nash for the testing of steel, iron, and all other metals, and all kinds of springs. They are well provided with machinery for preparing specimens to be tested. The machines are driven by a horizontal engine, to which steam is supplied from a locomotive boiler having a safe working pressure of 200 lbs. per square inch. The large testing machine is actuated by a three-throw pump, made by Messrs. Nasmyth Wilson and Co. of Patricroft. A special feature in connection with testing the specimens is an annealing furnace, in which they can be annealed without contact either with the flames or with the products of combustion.
CLYDE STEEL AND IRON WORKS.
Samuel Osborn and Co
At these works, the property of Messrs. Samuel Osborn and Co., the manufacture of Mushet's self-hardening steel has been carried on for many years. This special steel is made in crucibles in the usual way, and is chiefly employed for engineers' cutting tools. It possesses the property of becoming hard on simply being allowed to cool gradually in the air after forging; this is a great advantage in the production of milling cutters and many other tools, because the shape of the tool is less liable to become distorted as it so often does when made of ordinary steel and hardened in the usual way by sudden cooling. With tools made from Mushet's steel the cutting speed may be increased 25 to 50 per cent. beyond the ordinary speed without the cutting edge being injured by heat; but more care must be taken in dealing with the work, as the steel is harder than ordinary steel. Its specific gravity is 9 per cent. greater than that of ordinary steel, and it has a very close grain; it has not yet been welded, even by electricity. Mushet's titanic steel is also made here, including one sort that is weldable. It is specially adapted for mining tools and rock drills, and is not self-hardening.
The more ordinary branches of manufacture include various kinds of steel, from "extra best cast-steel" suitable for cutting tools, down to the cheaper qualities in which a durable cutting edge is not required. For railway springs, which are a leading branch of manufacture, the steel is rolled into bars and cut to the required lengths, the ends are ground, holes are drilled when necessary, and the leaves are cambered and built up. Steel shafting is produced by a combined action of rolling and reeling. The shaft is made hot and rolled between a pair of face rolls, which have their faces in vertical planes but not quite parallel, and are forced together by a screw actuated by a hand wheel. As they revolve in opposite directions, the shaft which is being rolled is spun round on its own axis at the same time that it is fed forwards, and it passes between the face rolls near to their circumferences.
There are three other iron and steel works in Sheffield belonging to the firm. One is a foundry in Rutland Road, for the production of steel castings up to 15 tons or more; another is a crucible-steel foundry in Bridge Street for special work. Here are made portable ramps for re-railing rolling stock, railway wheels, crank axles, buffer cases, horn blocks, crossings, propeller blades, paddle-wheel centres, steam-hammer tops, hydraulic cylinders, spurwheels and pinions, and various mining and engineering work. Machine moulding from the smallest to the largest gearing in use is done by four of Whittaker's moulding machines. At the Brookhill Works are manufactured high-class engineers' files, saws, machine knives, hammers, and similar articles. The four works together employ usually between nine hundred and a thousand hands.
Joseph Rodgers and Sons
This establishment, belonging to Messrs. Joseph Rodgers and Sons, occupies the whole block of buildings skirted by Norfolk Street, Milk Street, Sycamore Street, and Flat Street. The Rodgers family have been cutlers for at least two centuries. In 1730 the firm, consisting then of Maurice and Joseph Rodgers, removed from Hollis Croft to Sycamore Street, where, as the business increased, the premises were gradually extended and rebuilt, until in 1869 they occupied the whole of the present block with frontage in Norfolk Street. In 1764 they received from the Cutlers' Company of Hallamshire their trade mark, a Maltese cross and star. In 1800 they added to their original trade of penknife cutlers the manufacture of razors and table knives, and a few years later commenced that of scissors. About 1821 they were made by special appointment cutlers to the Royal family, which distinction they continue to enjoy. They now employ about 2,000 workmen.
In the show-room is a knife containing between 1,800 and 1,900 blades and instruments, all quite distinct and no two alike. Here is also shown the celebrated Norfolk knife, the blades of which are etched with portraits and views; the handle is of carved pearl, and represents hunting scenes.
DANNEMORA STEEL WORKS.
Seebohm and Dieckstahl
These works were acquired in 1869 by the present proprietors, Messrs. Seebohm and Dieckstahl, and by extensive alterations were transformed into crucible-steel works. The finest qualities of crucible cast-steel are made from bar steel which has been converted from Swedish wrought-iron manufactured from the Dannemora ore containing manganese; this natural manganese in the ore is of great value, as it will not do to add the manganese in the form of spiegeleisen or ferro-manganese to iron manufactured from an ore not containing manganese.
The wrought-iron having been rolled into bars about 3 inches wide and 5-8ths inch thick and 12 feet long, these are first converted into blister steel, in furnaces having the large conical stacks which form a conspicuous feature of works making crucible steel. The iron bars are placed in rectangular troughs, about 3 or 4 feet square and 12 feet long, called converting pots, which are constructed of refractory material. The pots are built into the bottom of the converting furnace, and a brick arch is turned over them with suitable flues; the fire is underneath the pots, and the whole is surmounted by the conical chimney. Each converting furnace holds altogether from 15 to 35 tons of iron in two pots; it is generally considered that better steel is produced from the smaller pots. A bed of hardwood charcoal is laid in the bottom of each pot; and above this are placed alternate layers of iron bars and charcoal, until the pot is full; it is then closed with a thick cover of wheelswarf, the silicious mud which accumulates at the troughs of the Sheffield grinding wheels; this substance resists long exposure to great heat, and renders the top of the pot practically air-tight. The fire is so regulated as to bring the mass of iron and charcoal to nearly a white heat, which is gradually reached in the course of six to nine days, according to the temper or percentage of carbon required. The temperature is then let down gradually, the furnace requiring eight or nine days to cool down before the bars can be drawn out of the pots. When the cover is removed from the pot, a certain portion of the carbon has penetrated into the substance of the bars and entered into combination with the iron, forming blister steel. It is necessary to prevent all entrance of air into the pots during the conversion or "cementation," otherwise the charcoal would be burnt and the iron might be oxidised. If the heat is not properly managed, the pots may crack during the process. The pots last for using from twenty to forty times. If the heat is raised too high, the bars become glazed by the melting of their surface. The proportion of carbon contained in the steel varies from 1/2 to 1 1/2 per cent. The blister steel containing 1/2 per cent. is known as a "spring heat," and that containing 1 1/2 per cent. as a "melting heat." The carbon is taken up by the surface of the iron bars, and penetrates further through their thickness according to the length of time the heat is maintained. In "spring heat" the interior of the bar remains iron, although the crystals have lost their brilliancy. In a "country heat," containing 5/8 per cent. of carbon, the crystals of steel on the edges have become more distinct. In "single-shear heat," containing 3/4 per cent. of carbon, there is more steel on the outside and less iron in the centre; until in a " double-shear heat," containing 1 per cent. of carbon, the steel and iron are about equal. A "steel-through heat," containing 1 1/4 per cent. of carbon, and a "melting heat," containing 1 1/2 per cent., are both of them all steel; in the former the crystals of steel are small, and in the latter a rather longer time in the furnace has rendered them large.
From the bars of blister steel may be made either shear steel or cast steel. Shear steel consists of bars of blister steel welded together and rolled or drawn down under a hammer. As the blister-steel bars have in neither case undergone conversion long enough to make them steel all through, the shear steel, whether single-shear or double-shear, is really made up of a mass of iron and steel mechanically mixed. The double-shear steel is twice welded: after the blister-steel bars have been welded together and drawn down to suitable size, they are then welded together again and drawn down a second time. The object of making shear steel is to obtain as far as possible the valuable qualities of both iron and steel in one material: namely the ductility or toughness of iron combined with the hardness of steel.
Cast steel is made from blister steel by melting it in clay crucibles, called " pots." The temper, that is the hardness or softness of the cast steel, depends upon the percentage of carbon in the blister steel. The quality of the steel depends upon the character of the Swedish or other iron from which it is converted. The pots are placed in a furnace beneath the floor, and the furnace is fired by coke piled around them. The bars of blister steel are broken up into small pieces, which are charged through a funnel into the pots while in the furnace; the process of conversion having changed the character of the metal, the bars are easily broken for the purpose by the hammer. When the melting pot has been charged, the lid is put on, and the furnace or melting hole is filled up with coke. The degree of heat has to be properly adjusted, as well as the time that the crucible is allowed to remain in the furnace; this part of the process therefore requires the exercise of care and judgment. After the steel has become liquid, it has to be boiled in the pot for nearly half an hour, which is called "killing," until it is " dead-melted "; the higher the quality of the steel, the more killing does it require. It is in this part of the process of melting crucible cast-steel that its advantage as compared with the Bessemer or Siemens process is considered chiefly to lie. The pots are used three times, after which they are so reduced in thickness as to be useless. The first melting, when the heat of the furnace has to be got up again after having been let down, occupies four or even five hours; for the second and third meltings, when the furnace is already hot, the time is reduced to two hours and a half. The charges are diminished as the pots wear: the first is generally from 50 to 70 lbs., and the third from 38 to 40 lbs., according to the size of the crucibles. When ready the pots are lifted out of the melting holes by tongs; care has to be taken not to crush the pot, while yet gripping it tight enough to prevent it from slipping. The cover having been removed, the metal is freed from slag by skimming it with a bar of iron having a lump of slag on its end, around which the slag floating on the molten metal solidifies. The liquid steel is then poured or "teemed" into the ingot moulds, which are made in halves and held together by iron bands.
This is the identical process of making crucible or cast steel which was introduced into Sheffield a century and a half ago by Benjamin Huntsman, and has continued unaltered to the present day. As the Swedish iron is procured of uniform quality, containing just the ingredients requited and practically free from impurities, there is the less need of continuous analysis; and the eye becomes so well trained by long practice, that it is said an experienced steelmaker can discriminate by the fracture the proportion of carbon to the minute extent of only one-tenth of one per cent., and even less.
ETNA EDGE-TOOL WORKS.
Spear and Jackson
These extensive works, belonging to Messrs. Spear and Jackson, are situated in Savile Street East, and have been established over a century for the manufacture of saws, files, and tools of almost all kinds. They are furnished with all modern facilities for the perfection of manufacture of these various productions, all of which are made and manipulated on the premises from the crude material up to the finished article. The firm make their own steel by the cementation and crucible process, rolling it into bars, rods, and sheets, as required.
One of the chief branches of the work here carried on is saw making. Rolled sheets of steel are taken from the mill and pared to shape in shearing presses. The blanks then have the teeth punched out in other presses; after which they are hardened, hammered, and straightened ready for grinding. The grinding is done between two stones placed one above the other, whereby both sides of the saw are ground simultaneously. The axes of the two stones are not exactly parallel, so that the grinding surfaces are also at a slight angle. By this means the back of the saw is made somewhat thinner than the toothed edge, thereby enabling the saw to clear itself in the cut. The surfaces are finished by means of wooden rollers covered with leather, on which emery powder is fed by hand. The saw is then sharpened and set by hand, and lastly fitted with handles.
In the department for making garden and field tools, steel shovels forged solid are a special article of manufacture. These are first hammered out of a solid block by a machine hammer, after which they are pared to shape by a shearing press. The piece, which is still flat, is then heated and dished to the required shape under a drop hammer. The strap, which is forged out of solid with the rest, is then riveted upon the wooden handle, and rounded to fit it by means of half rolls; after which the implement is completed by finishing portions of it on a leather band with emery. Digging and hay forks are forged solid, and the straps for attachment to the wooden handle are welded on. In the wood department, where shafts and handles are prepared for the different tools, the wood is steamed and bent into the various curved shapes required by means of a machine with dies, into which the wood is pressed by a cam action.
The steelmaking department comprises the usual crucibles and other appliances; and the sheet mill contains rolls to produce steel sheets up to five feet square. There is a large hammer forge, and a steam press for shaping plough boards and articles of a similar kind. A large file-making department produces files of all kinds for engineers, saw-mills, &c. Reaper and mower and hay and sugarcane knives, scythes, axes, chisels, plane irons, picks and mattocks, matchets, hoes, tools for paper mills and tanneries, mining tools, and many kinds of engineers' tools are also made.
BELLEFIELD SAND-BLAST WORKS.
In these works, situated in Bellefield Lane, Tilghman's Sand-Blast process has been carried on for nine years past. A jet of sand, propelled at a high velocity by a steam or air blast, is employed for cutting and producing ornamental carving on stone and other materials, grinding and ornamenting the surface of glass, sharpening and scouring files, cleaning castings and other metallic surfaces, and recently for artistic lithography. The hardest steel, chilled cast-iron, or other metal can thus be cut by a stream of quartz sand. For sharpening and scouring files, a stream of fine sand and water in the state of fluid mud, directed at a certain angle with the face of the file, is driven with great velocity by jets of steam against the backs of the teeth, and grinds away the burr or curl produced by the chisel, giving to the teeth keen and well-supported edges. Files so treated are found to cut faster, work more freely, and wear longer than the ordinary kind; and the process is now in operation at several of the largest file manufactories. When applied to the cleaning of brass, iron, or steel castings, the process entirely removes the sand, and the hard skin or scale which is found so destructive to the edges of files and cutting tools. When applied to lithography, the process consists in blasting out minute particles of the prepared stone, on which an outline has already been sketched, by means of a fine stream of sand propelled by an air blast from the nozzle of an instrument guided by hand. Sharp lines and tints of every degree of softness can be produced by varying the position of the instrument, the air pressure, and the quantity of sand escaping. The various applications of the sand blast are shown in operation at the works, and illustrate the progress made since the paper on this subject was read to the Institution seventeen years ago (Proceedings 1873, page 260).
Walker and Hall
These works, carried on under the name of the original founders Messrs. Walker and Hall, are situated in Howard Street, and were established about half a century ago by Mr. George Walker, immediately after the discovery of the process of electro-plating by Mr. Wright, a Sheffield surgeon. Starting with a few hands they now employ over 800 in the manufacture of all classes of goods from the nickel-silver base. The following processes are seen in operation:— casting of nickel-silver, stamping into shape, spinning of flat sheets into various forms, silversmiths' work, engraving, chasing, forging of steel blades, carving of ivory and pearl, mounting of steel and silver cutlery, sand buffing, burnishing, manufacture of spoons and forks, and electro-plating.
This colliery comprises four drawing pits, of which the two principal, situated about 11 miles from the Victoria Railway Station, Sheffield, raise coal from the Silkstone and Parkgate seams. Both of them are fitted with large winding engines, made by Messrs. Davy Brothers, Sheffield, which have now been at work for twenty-two years. The Parkgate engine winds from two levels, by means of two diameters of drum. Both engines are under the same roof, and are fitted with steam and foot brakes. The Silkstone workings are now at a great distance from the shaft; and the underground haulage is dealt with by a main and tail rope along a level over 2,000 yards in length; and from the further end of this level to the face by a main rope down a plane about 1,500 yards long, dipping on the average 1 in 10.
The engines working this system of ropes are at the surface. The main-and-tail-rope engine is a double direct-acting engine made by the Yorkshire Engine Co.; it was erected about September 1888. The main-rope engine is a double direct-acting condensing engine, and the drum is fitted with a special form of friction- clutch.
A new fan engine, made by Messrs. Walker Brothers, Wigan, has recently been erected. It is a compound engine, working a driving wheel of 16 feet diameter, which is geared by fourteen 11 inch ropes to an 8 ft. wheel on the fan shaft.
Seven steel boilers, made by Messrs. Hawksley Wild and Co., 30 feet long and 7 feet diameter, were erected in 1884, and are fitted with Proctor's mechanical stokers, which enable a very inferior class of coal to be used for firing. There is also fitted to this range of boilers a Lowcock's economiser, through which the water is sent into the boilers at a temperature of from 280° to 310° Fahr. The pumping at the colliery is very heavy, and a large Cornish beam engine with 86-inch cylinder and 10 feet stroke is kept constantly at work. To each end of the boiler-plate beans are attached the pump spears, namely 18-inch and 16-inch sets to the Silkstone seam at a depth of 220 yards, pumping up 110 yards to the Parkgate seam, to which there are two 26-inch sets at a depth of 110 yards, these two being equal to 2,000 gallons per minute.
There are three duplicate horizontal direct-acting compound pumping engines underground, made by Messrs. Hathorn Davey and Co., Leeds; they are fitted with 15-inch ram, and are each capable of pumping 1,000 gallons per minute. One pumps from the Silkstone to the Parkgate seam, and the other two from the Parkgate to the surface. A Priestman's petroleum engine has just been set to work in the Silkstone workings, geared to a Warner's three-throw pump, for dealing with the water in the dip workings.
The dry separation plant on the surface is very complete. It consists essentially of three sets of jigging screens, which separate the coal into three sizes; and four large travelling belts, on which the dirt is picked out from the coal. By this means the coal is mechanically divided into twelve different sorts, and the plant is capable of dealing with 250 tons of coal per hour.
At the Woodthorpe pit a Cockson fan is at work, which is driven direct by a Willans and Robinson engine making 280 revolutions per minute.
TINSLEY STEEL, IRON, AND WIRE WORKS.
These works, belonging to Messrs. William Cooke and Co., are situated at Tinsley, 2 1/2 miles from Sheffield. They were established in 1866, and comprise two blast-furnaces, one in and one out of blast, puddling furnaces, steam hammers for shingling, puddled-bar rolling- mills, and three merchant-mills, 14 inch, 10 inch, and 9 inch. There is also a steel-wire rod-mill, adapted for rolling rods in lengths suitable for telegraph wire; and two wire-drawing mills, engaged principally in drawing wire for ropes of all kinds; also complete appliances for galvanizing. For the manufacture of wire ropes, plant of the most modern description was erected in 1887, which is kept fully employed.
YORKSHIRE ENGINE WORKS.
Yorkshire Engine Co
These works were built in 1866 for the manufacture of locomotive engines upon a large scale. Circumstances however having since directed part of that trade into other channels, they are now mostly employed upon general engineering work, including all classes of stationary engines, torpedo engines, and boilers for locomotive, stationary, and marine engines. Light locomotives of different kinds, weighing only 3 tons, are now in course of construction for railways of 18 inches gauge, as well as the heaviest class of Fairlie engine having twelve wheels and weighing 86 tons. Other locomotives of this class are being built for 3 ft. 6 ins. gauge; also four-wheel and six-wheel engines for collieries and contractors, as well as a locomotive to be driven by electricity. Special machinery has been put down for finishing marine forgings and castings of the heaviest description, which have been supplied for war ships and American liners. A quantity of work for the Admiralty is now in hand; also air-compressing machinery, colliery plant, and coal-cutting machines. The works comprise a large machine-shop, fitting shop, and boiler shop; a foundry having a 30-ton overhead travelling crane, Root's blower, and every facility for producing castings up to 50 tons. The forge comprises four hammers, and large smithy. There is also a capacious erecting shop, well provided with steam-power, overhead cranes, &c. The works cover ten acres, and employ between 500 and 600 men. They are connected with the Manchester Sheffield and Lincolnshire and the Midland Railway, the nearest station on the former being, Meadow Hall and on the latter Wincobank.
ALDWARKE MAIN COLLIERY.
At this colliery, belonging to Messrs. John Brown and Co., there are a pair of horizontal winding engines with cylinders 36 ins. diameter and 6 ft. stroke, raising with flat ropes 150 tons of coal per hour or 1,500 tons per day from a seam 51 feet thick at 430 yards depth; the cages are double-decked, each cage taking six tubs; the time occupied in the lift is 47 seconds, and in the banking of the six tubs 5 seconds.
The oscillating screens and picking bands are adapted for sorting and cleaning 250 tons per hour. Also another pair of horizontal winding engines with cylinders 22 ins. diameter and 4 1/2 ft. stroke, raising 100 tons per hour from a seam 5 feet thick at 230 yards depth; and oscillating screens and picking bands for sorting and cleaning 150 tons per hour. Three pairs of horizontal hauling engines, with cylinders 14 ins. diameter by 2 1/2 ft. stroke, and 22 ins. diameter by 4 ft. stroke, and 24 ins. diameter by 4 ft. stroke, are fixed at surface, the ropes being carried down the shafts in pipes. Two Schiele fans 14 ft. diameter are driven by belting from engines with cylinders 24 ins. diameter by 3 ft. stroke, and 22 ins. diameter by 3 ft. stroke; and each fan produces a current of 200,000 cubic feet of air per minute. Slack grinding, washing, and coking in beehive ovens are carried on to the extent of 1,200 tons of coke per week. A miners' safety-lamp testing apparatus is employed, similar to that used by the Royal Commission on accidents in mines; the ignited lamp to be tested is placed in a chamber with a glass side and loose lid, and an explosive current of gas and air mixed in known proportions is passed through the chamber at a measured velocity.