SfX WILLIAM SIEMENS, F.R.S. 89 



The initial heat of the gas is therefore made available for produc- 

 ing a plenum of pressure by making the gas rise about 20 feet 

 above the producers, then carrying it horizontally 20 or 30 feet 

 through the wrought iron tube J, Plate 7, and letting it again 

 descend to the furnace, as shown by the arrows in Fig. 1. The 

 horizontal tube J being exposed to the atmosphere causes the gas 

 to lose from 100 to 150 of temperature, which increases its 

 density from 15 to 20 per cent, and gives a preponderating weight 

 to that extent to the descending column, urging it forwards into 

 the furnace. 



The application of the regenerative gas furnace as a plate glass 

 melting furnace is shown in Plates 9 to 12, which represent a 

 melting furnace now in course of erection at the British Plate 

 Glass "Works near St. Helen's. This furnace does not differ 

 materially from the regenerative gas furnaces previously erected 

 and at work at Messrs. Chance's and Messrs. Lloyd and Summer- 

 field's, but is selected in preference because it is the most improved 

 in details of construction. Plate 9 shows a longitudinal section of 

 the furnace, Plate 10 a transverse section, and Plate 11 a sectional 

 plan above and below the bed or " siege " as it is termed of the 

 furnace. Figs. 7, 8, and 9, Plate 12, show the detail of the gas 

 and air valves. 



The heating chamber A of the furnace, Figs. 4 and 5, contains 

 twelve glass pots B, which are got out through the side doors 

 when the glass is ready for casting upon the moulding table. 

 Underneath are placed transversely the four regenerators C C, 

 composed of open firebricks built up on a grating, which are 

 arched over at the top and support the bed or siege D of the 

 furnace. The regenerators work in pairs, the two under the right 

 hand end of the siege communicating with that end of the heating 

 chamber, while the other two communicate with the opposite end, 

 as shown in Fig. 4. The gas enters the chamber through the 

 three passages E, Figs. 5 and 6, and the air through the two 

 intermediate passages F, whereby they are kept entirely separate 

 up to the moment of entering the furnace, but are then able 

 immediately to mingle intimately, producing at once an intense 

 and uniform flame in the heating chamber. The siege D is built 

 of firebrick, with a number of transverse channels, shown black in 

 Figs. 4 and 8, through which the cold entering air is made to 



