in. PiuaiE MOVERS. 455 



The- engine was designed and patented by Mr. P. Brotherhood in 

 1872-73. Brotherhood and Hardingham, Engineers, London. 



South Kensington Museum. 



1956a. Model of Brotherhood's patent Three-cylinder 



Hydraulic engine arranged for turning a. capstan, the pressure 

 being supplied to the engine by a Brotherhood's patent three-cylinder 

 pump. Hydraulic Engineering Company, Limited. 



1967. Model of horizontal engine (novel girder pattern), 

 with portion of cylinder removable to show the action of a variable 

 automatic expansion valve gear (Rider's patent), controlled directly 

 by the governor. The expansion valve works on the back of the 

 lower valve by a separate eccentric in the ordinary manner, but 

 owing to its triangular shape, and the form of the parts, the point 

 of cut-off changes according to the angular motion of the valve 

 round its spindle. This angular rotation is produced by the rise 

 and fall of the governors through rack and quadrant. Any 

 acceleration in speed thus affects the rise and fall of the governor 

 balls, and accelerates or delays the time of steam admission. 



Hay ward Tyler fy Co. 



1981. Model of Robey and Go's, semi-portable mining and 

 winding engine. Richardson's patent. Robey and Co., Lincoln. 



South Kensington Museum. 



1957. Working Model of a stationary steam engine. 



Royal Trade School, Halle (Director, Di\ Kohlmann). 



2178ggl. Drawing of a Portable Engine, 1828. 



Maudslay, Sons, and Field. 



1945. Atmospheric Gas Engine. Otto Langen and Cross- 

 ley's joint patents. Actuated by the vacuum resulting from the 

 explosion of common coal gas and air. Crossley Brothers. 



In this engine, which works by the vacuum resulting from the explosion of 

 common coal gas and air, the piston is not, as is usual, connected with the 

 shaft on both up and down stroke, but on down stroke only. It is thus at 

 liberty to fly up freely from the force of the explosion, which takes place at 

 the bottom only, and by driving the piston before it empties the cylinder of 

 air through its open upper end. The return of the air on the down stroke 

 yields the driving power, and turns the shaft by means of a friction clutch, to 

 which the piston is geared by the rack. The vacuum beneath the piston in 

 equal to about 11 Ibs. per square inch for the greater part of the down stroke. 

 The governor does not act, as is usual, by increasing or decreasing the power 

 of each stroke, but by varying the number of strokes, each being of the same 

 power. This is done without materially changing the speed of the shaft. 

 Three or four explosions per minute are generally sufficient to turn the engine 

 itself, and as a maximum of 30 to 35 may be made, there is a balance of, say, 

 from 26 to 32 strokes or explosions per minute left to be applied to useful work 

 under the regulation of the governor. As this engine can be started and 

 stopped at a moment's notice, giving full power at once, and is free from the 



