Cooper'' s Rotative Piston. 319 



a continued discbarge effected, by one and the same opera- 

 tion. As a further illustration of the point in question, it 

 may be observed, 



It can he worked with one half the power. 



The air vessel is totally dispensed with, and the power is 

 applied directly upon the water. It operates on no more 

 than it discharges. On the other hand, as a consequence of 

 the alternating motion of the piston engines, twice the sur- 

 face is acted upon, and ihQ friction of course is comparative- 

 ly twofold. This is not all. The power necessary to over- 

 come the inertia of the water is both exerted and suspended 

 at every stroke of the piston. But in the rotative the cur- 

 rent flows instantly, continuously, and uninterruptedly. 



Connected with this part of the subject is a fact of the 

 first importance. The extreme necessity of prompt and ef- 

 ficient action in case of fire, is beyond controversy. A suffi- 

 cient number of men to work the rotative engine with effect 

 may be readily and easily convened, either in cities or villages ; 

 while a delay .^ waiting the arrival of the number necessary 

 to work the old engines, might result in a total destruction 

 of property. 



It is comparatively proof against frost. 



Those acquainted with the old engines, know, by sad ex- 

 perience, the evils of frozen valves and obstructed pistons, 

 and that it is necessary to resort to means of thawing out the 

 machine^ or to suffer it to remain useless, even at times of fire. 

 But a single revolution of the rotative, discharges the ice 

 that may have collected on the surface exposed, and an ef- 

 fective operation is not retarded for a moment. 



It discharges a more condensed column. 

 It is apparent to the man of chemical science, if not to 

 the common observer, that water, in the form, of spray ^ 

 thrown into an intense flame, is instantly decomposed,* and, 

 instead of diminishing, increases its fury. The advantage of 

 the rotative herein, as before observed, consists in dispensing 

 with the air vessel. In the old machine it is indispensable. 

 Yet, notwithstanding its use and importance to them, it con- 

 stantly imparts a portion of air to the water discharged, and 

 thus far produces the evil complained of 



* Giving its osygeu to the carbon, to increase its ignition, and its hj'drogen 

 to augment the volume of flame. — Editor. 



