82 . i>HILOSOPHICAL TRANSACTIONS. [aNNO 1757. 



produced by the same fire without blowing air through. He then applied a ma- 

 chine of this kind to the engine at the York-buildings water- works, the boiler 

 of which is 1 5 feet diameter. It has a double concave, with a kind of door- 

 way or passage from one to the other, to let the flame pass, as it were, through 

 and round the water; by which means there is no-where above Q inches of water 

 to be heated through, though the boiler is so large; and which, by 3 years experi- 

 ence has been found to require 4- less fuel than any other fire engine of equal size. 



Mr. F. fixed a pipe, of an inch and a half diameter, to a pair of double 

 bellows 3 feet diameter; which pipe reached about I foot under the surface of 

 the water in the boiler, to the end of which are fixed horizontally 2 branches, 

 each about 8 feet long, tapering from 1 inch diameter to about ^ o^ an inch. 

 These branches are bent in a circular manner, as in the plan, to answer the form 

 of the concave, and are perforated with small holes about 4 inches distant at the 

 thickest part, and decreasing gradually in distance, to within ^ of an inch to- 

 wards the small end. The reason of these branches being made taper, and the 

 distance between the holes decreasing to the small end, was in order to give the 

 greater power to the air forced by the bellows to discharge the water lodged in 

 such a length of pipe; and he observed by this method, that the water was gra- 

 dually forced through the holes to the end of each branch, and seemed to throw 

 an equal quantity of air through the water. The length of the pipe, to which 

 the branches are fixed horizontally, is about 18 feet to the nosle of the bellows: 

 and yet the steam, that passed through the pipe into the bellows, was so hot 

 before the water boiled, as to force through the leather: but this he easily reme- 

 died, by fixing a brass cock of 1-^ inch diameter to the pipe, which hindered the 

 steam from ascending, till the engine was ready to work : and being opened, the 

 air continually keeps it cold till the engine has done working; then the cock must 

 be shut again. 



The bellows is worked by means of a small lever, and pulleys applied to the 

 great lever of the fire-engine, which keeps a continual blast while the engine 

 works, the strength of which is increased or diminished, by adding or taking 

 oflf the weights on the bellows. 



The effect produced was, first, a very visible alteration for the better in the 

 working of the engine. When the fire was stirred, as it must be every time 

 fuel is added, the steam generally became too fierce, which occasioned great 

 irregularity, and sometimes, if not watched, great damage to the engine; and 

 when the fire abated, the stroke became immediately much shorter, or stopped 

 entirely, if fuel was not soon added, whereas, by blowing air thus through the 

 tvater, it keeps, with any moderate care, an equal stroke to its full length, 

 from the beginning to the end; and by that means discharges a considerably 

 greater quantity of water. iii 



