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So4 7 sien ܚܣܚ la ܚܝܩܝܝܣܚܫܣ Later a small company was formed for the purpose of carrying out these experiments on a more extensive scale, for while Lubbers was actually making window glass cylinders, there were a great many difficulties still to be overcome in order to render his apparatus suitable for the manufacture of window glass in a commeruial way. As a matter of fact, it required years of work and an enormous amount of money to develop the apparatus to the point where it was BLOWING WIN DOW (LASS CYLIN DERS 3Y HAN). About 40 per cent. as the window plast production of the L'nited States is nacle by this method. finally operated at a profit. Nevertheless, the machine of today still retains the basic features of the Lubbers inventions, and, considering how completely, they revolutionized the established processes of window glass manufacture, his ideas, as set forth in his various patents, show a surprising knowledge of the essential conditions for mrking glass cylinders by machinery. The Lubbers process is a process for drawing cylinders vertically from a bath of molten glass. This in itself was not a new idea, as several patents-one dating back as far as 1854proposed this. Lubbers, however, was the first to devise a workable method for really doing it, a process that took into account the peculiar conditions actually involved in working molten glass, and apparatus that actually made glass oylinders-cylinders that were in every respect similar to those that were blown by hand. ANATHBANDHU. Volume I. re rr -dm The experiments were continued at Alleghny, Pa., until the spring of l902, when a factory at Alexandria, Indiana, was leased to Iubbers and the work was transferred to that point. There was a 54-blower continuous tank furnace at this plant, with all accessory flattening and other equipment for this capacity, and the machine installation was designed with a view to testing it out on a practical working scale, and to developing it as rapidly as possible to the point where it could be utilized. The work of developing and improving the various parts of the apparatus continued for about two years longer before satisfactory results began to be obtained, but finally there was perfected a machine that is today producing results far beyond the most optimistic expectations of its inventor. One by one the causes of the troubles were located and the apparatus modified or adjusted to correct then. "That this work was so slow and so di filieult was largely due to two facts: first, that in the liquid state in which glass is worked in machine operations it is so soft as to be extremely sensitive to changes in tenperature or variations itu exterior or interior fressure exerted at the point of draw; and, second, that in working glass, cooling strains develop as the glass passes from the liquid to the solid state, causing brittleness. The method of reheating the residue remaining in the pot after drawing a cylinder and then ladling fresh glass into the pot was not very satisfactory. It was difficult to get good quality of glass, for unless the glass in the pot and that which was ladled into it were heated to the same temperature and brought to a very fluid condition, they would not mix properly, and thus produce streaks in the cylinder. Similar difficulty was experienced in melting back the aresidues in the forehearth; if the glass was heated hot enough and sinmed when necessary in the manner employed in skimming the gatherers' rings in hand operation, the quality was satisfactory, but the operation was very slow,