1 88 THE SCIENTIFIC PAPERS OF 



through its owii slow combustion aids the gas, which per s& is at 

 the present time at all events the more expensive fuel. If gas 

 could be supplied at Is. a thousand feet, it would no longer be 

 more expensive than coal, and the time will come, I believe, 

 when we shall have good heating gas supplied to us at that price. 

 Wherever gas fuel is used, there ought to be some means of 

 accumulating the effect of heat some mode of regeneration, 

 and the question occupied my mind in my leisure hours, how 

 could the regenerative principle be applied to an ordinary open 

 fire-grate ? After some time the idea occurred to me, that in 

 taking advantage of the conducting power for heat of some metals, 

 I might be able to pick up heat at the back of the fire-grate, 

 and bring it down to a system of surfaces below the fire-grate, in 

 order there to communicate it to currents of air supporting 

 combustion in front of the grate. 



Such an action is carried out in the grate of which I have a 

 model here, Plate 35. It has the ordinary fire-bars, to the bottom- 

 most one of which an inclined plate is attached, but instead of the 

 ordinary horizontal grate, an angular casting of iron with ribs 

 projecting from its lower surface supports the fuel. In front of 

 this casting, and behind the lower grate-bar, a gas-pipe is fixed, 

 having a limited number, (from 8 to 12) of gas orifices, of about 

 one-sixteenth of an inch diameter. The gas issuing from these 

 openings towards the back of the pipe, gives rise to flames percola- 

 ting through the coke oranthracite, or other similar substances which 

 fill the grate. Each gas flame in percolating up through the coke 

 produces very much the appearance of an ordinary coal fire in its 

 best condition, and the coke in front of the grate soon becomes 

 incandescent, giving out a very considerable amount of radiant 

 heat. When this point has been reached, the gas may be nearly 

 altogether turned off, as the glow of heat will be maintained 

 almost entirely by the hot air currents which by this time set in, 

 and produce intense combustion in front of the grate. I have, I 

 think, fourteen such grates in my office and house, including all 

 the principal rooms, and I have succeeded gradually in winning the 

 lady portion of the household over in favour of the improvement. 

 At first they said it was a dead fire, and you could not poke it, 

 but gradually even the housemaids, who at first thought it was an 

 abomination, have come round. They see that it gives them less 



