4 THE SCIENTIFIC PAPERS OP 



Condensing water, however, is generally obtained at the tempera- 

 ture of about 60 Fahr., and it leaves the condenser at about 

 110 Fahr., which latter temperature implies a remaining atmos- 

 phere of vapour equal to 2'5 inches of mercury, or in other words 

 a vacuum of 27'5 inches below the atmospheric pressure at 30'0 

 inches. If a smaller quantity of condensing water be used, it will 

 be raised to a proportionately higher temperature, and a less 

 perfect condensation will be effected. At 212 Fahr. the pressure 

 of the uncondensed vapour would be equal to that of the atmos- 

 phere, and the object of the condenser would be entirely frus- 

 trated. 



In all cases where an abundant supply of condensing water 

 cannot be obtained, or where the heafc of the steam employed by 

 the engine is reclaimed for other purposes, steam engines are 

 worked without a condensing apparatus, or at high pressure, at 

 the sacrifice of an effective pressure nearly equal to that of the 

 atmosphere upon the working piston. The regenerative con- 

 denser, forming the subject of the present paper, redeems the 

 engine from this waste of heat in the one case and loss of 

 mechanical effect in the other case, being possessed of the peculiar 

 property of returning the condensing and condensed water at the 

 initial temperature of the steam previous to its discharge from the 

 working cylinder, commonly speaking at 212 Fahr. ; producing 

 nevertheless an efficient vacuum. 



Fig. 1, Plate 1, shows a sectional elevation of the regenerative 

 condenser, as applied to a 10-horse-power high -pressure engine. 

 It consists of an upright rectangular trunk of cast iron A, the 

 lower end B of which is cylindrical, and contains a working piston 

 C. The trunk A is filled with metallic plates D, which are placed 

 upright and parallel to each other, with intervening spaces of not 

 less than 1-1 6th inch in breadth. The upper extremity of the 

 condenser communicates on one side E to the exhaust port of the 

 engine ; and on the other to the hot well F through a valve G. 

 A stop H prevents the opening of the valve beyond a certain 

 distance, in order that it may shut again more instantaneously. 

 The metallic plates D are fastened together by five or more thin 

 bolts, with small washers between the adjacent plates, which keep 

 them the required distance apart. They can easily be removed 

 from the condenser for the purpose of cleaning, by taking off the 



