urposely introduced at the bottom of the arrangement, is first raporized 

 " " " ■ uited fuel and rearranged as 

 nd carbonic oxyd; and 

 only the ashes of the coal are removed as solid matter from the chamber 

 at the bottom of the fire-bars. 



These mixed gases form the gaseous fuel. The nitrogen which en- 

 tered with the air at the grate is mingled with them, constituting about 

 a third of the whole volume. The gas rises up a large vertical tul>e for 

 12 or 15 feet, after which it proceeds horizontally for any required dis- 

 tance, and then descends to the heat-regenerator, through which it passes 

 before it enters the furnaces. A regenerator is a chamber packed with 

 fire-bricks, separated so as to allow of the free passage of air or gas be- 

 tween them. There are four placed under a furnace. The gas ascends 

 through one of these chambers, whilst air ascends through the neighbor- 

 ing chamber, and both are conducted through passage outlets at one end 

 of the furnace, where mingling they burn, producing the heat due to their 

 chemical action. Passing onwards to the other end of the furnace, they 

 {i. e. the combined gases) find precisely similar outlets down which thej 

 pass ; and traversing the two remaining regenerators from above down- 

 wards, heat them intensely, especially the upper part, and so travel on in 

 their cooled state to the shaft or chimney. Now the passages between 

 the four regenerators and the gas and air are supplied with valves and 

 deflecting-plates, some of which are like four-way cocks in their action; 

 so that by the use of a lever these regenerators and air-ways, which were 

 carrying off" the expanded fuel, can in a moment be used for conducting 

 "' ' ' ■> the furnace ' ' '" "' '' 



^y air and gas into the furnace, i 

 ck. It is to be observed that th( 



ved that the intensely-heated fiame whicli -- 

 tne turnace tor ttie stack always proceeds downwards through tho ' 

 erators; so that the upper part of them is most intensely ignited, k 

 back, as it does, the intense heat ; and so etfectual are they in this 

 that the gas which enters the stack to be cast into the air is not u- 

 above 300° F. of heat. On the other hand, the entering gas and air al- 

 ways pass upwards through the regenerator ; so that they attain a teiu- 

 perature equal to white heat before they meet in the furnace, and there 

 add to the carried heat that due to their mutual chemical action. 1^ J* 

 considered that, when the furnace is in full order, the heat carnefl 

 forward to be evolved by the chemical action of combustion is abou' 

 4000°, whilst that carried back by the regenerators is about 300U , 

 making an intensity of power which, unless moderated on purpose, wou 



i regenerators are alternately heated and cooled by tl5«.<"l*^^ 

 tering gas and air; and the time for the alternation is f 

 nait an hour to an hour, as observation may indicate. The motive po*" 

 on the gas is of two kinds— a slight excess of pressure within is kept up 

 from the gas-producer to the bottom of the regenerator to prevent »" 

 entering and mingling with the fuel before it is burnt ; but from the w 

 nace, downwards through the regenerators, the advance of the beat^i 

 medium is governed mainly by the draught in the tall stack, or chimaey. 



Great facility is aff'^-'^"-^ — '^- - -'' -^ f., maces, i'' 



wliilst glass is in the c 



