It is curious to note, that while the glass manufacture in most of its forms has prospered in this country, and factories have multiplied almost without number, yet the manufacture of plate glass has been almost quite left out, and there is at present but one rough plate glass works in operation in the United States, and only one in process of erection. We propose, therefore, to describe the processes connected with its manufacture in England, hoping-that our efforts will be of some use, or, at any rate, will be of interest. There are at present six plate glass factories in England ; namely, three at St. Helens, Lancashirethe British plate glass factory at Ravenhead, the Sutton Company, and the Union Company one at Newcastle-upon-Tyne, one at London, and one at Smeth-wick, near Birmingham. The British company is the oldest established, having been in successful operation nearly 200 years, the manufacture having been introduced from 'Venice somewhere in the seventeenth century, and established at Ravenhead shortly after. Three of these British factories melt their " metal " in the Siemens furnace, a process which is also used by the works now in existence in Massachusetts. The process of melting and casting the glass may be familiar to some, but it will be new to most of our readers. The mixture was formerly melted for twenty hours in a pot or crucible,'and then ladled out into a-other vessel called a " cuvette," which was placed by its side in the furnace. But jthis operation is now dispensed -with, and the glass is cast direct from the pot after a melt of from fifteen to twenty hours. A description of one factory -will necessarily be a description of all, and therefore we will give an account of the Birmingham factory from personal observations made at that establishment. The casting house is a building of about one hundred yards long by twenty-five 'wide. The furnaces are in the center of the building and the annealing ovens are arranged along Ijhe whole length of the room on both sides. The pot room, mixing room, and coal sheds, are arranged conveniently around the outside of the building. The mixture being placed in the melting pot, by installmentsthree fillings being the usual numberis gradually melted down into a homogeneous mass ; its perfect fusion is tested by dipping an iron rod into the pot, and drawing a portion of the metal out with it. When the metal is ready for casting, it is allowed to cool down for about an hour. The furneoe is the opened and a pair of tongs ax- ranged on wheels, is thrust into thef urnace and made to clasp the pot, which is drawn outiind placed on a carriage rxmning on a railway to the casting table. The contents are skimmed until all the droBS is removed, and the pot is then run up to the side of the table where it is lifted by a crane and tilted over on to the casting table, a large inass of cast iron, about twenty feet long, with side ribs to prevent the metal from flo'wing off. It is then rolled by a massive iron roller, and as soon as the plate is cool enough to admit of its being moved without crushing it, it is slid off into the annealing oven, which is just on the other side of the table. The table is also on rails, so as to admit of being moved from one oven to another. The plates, after being placed in the annealing ovens, are allowed to stay there, from a week to ten daysthe longer the better. "When taken out they are either taken to the grinding shed to be submitted to the second process or cut into proper sizes and sent away as rough plate, to be used as skylights, pavement, etc. The plate to be finished for look-ingglasses, windows, etc., is then laid on a grinding bench, which may be briefly described as follows : The machinery is nearly all under ground, in a vault, which runs the whole length of the room. The driving shaft from the engine runs in this vault, and is supported by bearings between every bench. This shaft is horizontal and drives a vertical shaft by means of bevel gearing. The upright shaft carries a clutch for the purpose of starting and stopping the machine. The vertical shaft is in the center of the machine, the working part of which is ten feet square, and which has four corner shafts ; each of the five shafts has a crank which, iiS turn, supports and moves a fly, which is literally a square of cast iron having long rods extending from it on both ends, which move with an alternate rectilinear motion, and with a kind of lateral swing at the same time. The glass is laid down and fixed with plaster, on firm stone tables, one on each side of this machine, and these connecting rods move runners over them at a rate of sixty revolutions per minute. The runners are composed of a wooden framework, faced with either iron plates, or with another plate of glass, and sand and water ar?thro?vn between the two surfaces by a boy until the whole is sufficiently groxmd. The Birmingham company have in operation t iventy-six grinding machines, which turn out a total weekly product of upwards of twelve hundred feet of glass. It should be stated that after the sand grinding, emery of three different degrees of fineness is used before the plate is take-up. , When the glass is fully ground it is raised up and taken to the smoothing shop, where it is smoothed. Formerly this operation was performed entirely by hand, the plates of glass being laid one upon another, having courses of emery running from No. 4 to No. 7 bet?V?en them, and being plentifully supplied with water. This operation is very similar to grinding, but is a great deal finer and slower. It is now almost universally performed by machinery, the machine being on the same principle as the grinder, but vith a speed of only fourteen revolutions a minute, whereas the grinder has sixty. "When the glass is smoothed it is taken to the polishing shop, where the finishing process for window plate is given. In the polishing room the glass is again laid on tables and the polishing is performed by means of two bars, which run longitudinally over the glass, carrying blocks which are covered with felt ; t'he table on which the glass is fixed by means of plaster, at the same time traveling, alternately from right to left, and viae, versa. The glass, during the process, is sprinkled plentifully with a mixture of the red oxide of iron aud water until sufficient pol'sh is given, when the plate is taken off and taken to the warehouse, or, if required to be silvered, it is carried to the silvering room, where that process is performed. However, this process is so well known that it is needless to describe it. Large quantities of this glass are sold in the country and much of it is also exported. So much for British plate glass. We will now turn to the American side and see what is the progress of plate glass there. Some fourteen years ago an attempt was made by a New York company, to commence a factory at Williamsburgh, N. Y., and one or two plates, were really cast, but the enterprise failed. A short time after a couple of window glass blo?vers and a few capitalists made the attempt at Chelsea, Mass., and shortly after at Lenox, in the same State, still in operation there, and the one alluded to above. It was attended with a large measure of success in the casting of rough plate. Some years ago they commenced experiments with a view to polishing, and a gentleman from Chicopee.in conjunction with some of the stockholders of the company, have patented an invention for that purpose, but from some cause or other they do not seem to be making much progress. Last year they commenced using the gas furnace of Siemens, and are still using it. For a long time the Lenox works was the only establishment of its kind in the United States, but now a rival is to appear on the scene. This is situated at New Albany, Ind., and is owned by Capt. J. B. Ford, a gentleman whose public spirit has done much for that city. He has already set in motion several founderies, glass and other factories, and last winter turned his attention to plate glass. He is about to commence its manufacture on a 'large scale, and the buildings for that purpose are far advanced towards completion. He expects to make glass by the middle of October. Mr. Bankard, one of the original plate-glass makers of Lenox, has been engaged by Capt. Ford to superintend the making of his glass. Capt. Ford intends to commence polishing immediately, on the European plan, and to effect this has ordered several machines from St. Helens, England, and has the services of an experienced glass polisher from that country. The word fail is not in Capt. Ford's dictionary and this enterprise cannot fail of success. As soon as this enterprise gets fully under way the readers of the SciBNTiFic AMBEICAN are promised a detailed ao eojivt of the establishmeut; Improvement In Turbine "Water "Wheels, It is a well-known fact that whenever the flow of water through the buckets of a turbine wheel has its velocity diminished by the lo-wering of the head, a better result is obtained by diminishing the spaces between the buckets. The writer has often descended, in such an emergency, into the wheel pit to adjust the buckets of one of these "wheels which were supplied with movable plates at their outer border, held by set screws ; a tedious operation and one requiring great judgment to perform with any approximation to accuracy. The invention herewith illustrated is intended to furnish a simple and ready means whereby the buckets may be adjusted as the head varies, either while the wheel is in motion or at rest, by hand, or by the action of a regulator. Fig. 1 is a perspective view of a center discharge wheel with portions of some parts broken away to show better the construction of other parts. The toothed wheel. A, has a female screw cut through the hub, which plays on the male screw, B, elevating it .or permitting it to fall as desired, through an oblong opening in the supporting framework, C. The oblong opening fitting over the oblong shank, D, of the screw, B, prevents its turning on its vertical axis, while it is free to move upward or downward as the wheel. A, is rotated one way or the other. The head of the screw, B, is a rectangular fram e, E, through the lower horizontal part of which an opening admits a shaft, whiih descends through the hollow shaft, Gt, of the water wheel, to the interior of the water wheel. An upper and an under collar, H and I, are fastened to the shaft, F, by set screws, as shown in the engraving, so that F must obey the motion of the screw, B. The water-wheel shaft, Gt, rests upon the usual step at the bottom of the wheel. The lower end of the water-wheel shaft, G, is slotted to permit the passage of horizontal arms, J, attached to an enlarged portion, K, of the shaft, P. The arms, J, "with the circular frame, L, and slotted brackets, M, attached to L, rise and fall with the shaft, F, as acted upon by the screw, A. The slotted brackets, M, are inclined to the circular frame, L. In the slots of these brackets (one to each bucket) play pins, N, fastened by a screw bolt to the top edge of the "buckets, 0. The receiving, or outer ends of these buckets are fixed, being cast?vith the rim of the wheel ; the inner, or discharging ends are movable, being pivoted to the fixed ends of the buckets in the manner of a rule joint. The operation of the parts is as follows : As the wheel. A, is turned to the left or right,the shaft, P, is lifted or depressed, carrying with it the parts, J, K, L, and the brackets, M. The inclined slots of these brackets act upon the pins, N, and these being attached to the movable inner, or discharging ends of the buckets, open them or close them as desired. The upper part of the rim is recessed to allow the motion of the pins, and at the same time to allow the top of the bucket to move closely to the rim. The pins are thus placed above the current of water and out of its way. Pig. 2 shows a plan of the buckets, pins, and slotted brackets, when the buckets are pivoted to swing horizontally. Fig. 3 is an elevation of the buckets when pivoted to swing vertically, sho-wing an extension of the principle to wheels of this description. It will thus be seen that the improvement is equally applicable to turbines of all kinds, and not only does away with a great inconvenience but adds to their* efficiency. Patented, March 9, 1869, by Jesse Newlin, whom address for further information, care N. "W. Newlin, 3303 Cherry street, Philadelphia, Pa.
This article was originally published with the title "The Manufacture of Plate Glass in England and the United States"