Sept. 1, 1864.] THE TECHNOLOGIST. 



THE MANUFACTURE OF TLATE GLASS. 63 



one-third more than the old machines are capable of doing, due allow- 

 ance being made for the difference of area in them. 



The first point to which attention should be directed for working out 

 further improvement is the method adopted in casting the plates of 

 glass, and the machinery employed to carry out the process. It has 

 been stated that the plates of glass in their rough state are very irregu- 

 lar, so much so that about forty per cent, of the glass is ground away in 

 the subsequent processes, which is a serious waste of material, and entails 

 a great expenditure of time and material in the process of grinding ; it 

 is therefore worthy of consideration, whether some improvement may 

 not be carried out in this direction by obtaining the plates of glass 

 smoother in the first instance. The grinding and smoothing operations 

 are believed to be now improved upon the previous practice, though 

 there is no doubt room for further practical suggestions and appliances. 

 The polishing process has been tried to a limited extent on the revolving 

 table last described, but without any practical advantage : the present 

 system is no doubt theoretically correct, as the action of the rubbers is 

 regular and uniform over the whole surface of the glass, thus keeping 

 up a uniform temperature ; but some motion producing a continuous 

 movement of the rubbers, instead of the present alternate movement, 

 would no doubt reduce the wear and tear and require less power, and 

 would probably also be found capable of a higher velocity, resulting in 

 an increase of production, provided the other requisite conditions of the 

 process were complied with. 



In the course of the discussion which followed, Mr. F. J. Bramwell 

 observed that reference had been made in the paper to the highly satis- 

 factory working of Mr. Siemens' regenerative gas furnace as applied for 

 melting the materials to make the glass at the Ravenhead Works : he 

 had, as engineer to the company, recommended the adoption of that 

 furnace for the purpose, being convinced of the great advantages that 

 would be found to attend its use, and the first furnace on that construc- 

 tion had now been in constant work for fifteen months, and a second 

 and larger furnace had been erected in May last, which had also been in 

 constant work since that time. These furnaces he believed left nothing 

 to be desired as far as regarded the melting ; but in other respects he 

 thought the process of making plate glass was at present in a most un- 

 satisfactory position, and some improvements seemed to be much wanted 

 in the mechanical contrivances used in the manufacture, though he 

 must admit it was more easy to make that assertion than to show how 

 the improvements were to be effected. A serious objection to the pre- 

 sent arrangements was the great amount of handling that the plates of 

 glass had to undergo in the several processes, which was evidently an 

 important point when it was considered that the large plates fetched a 

 higher price per square foot than smaller ones, and therefore it was de- 

 sirable to avoid the risk of having to cut up large plates into smaller 

 sizes on account of fractures. Under the present methods, however, the 



