414 Account vf a New Hydraulic Machine. [Dko. 



level of the water in the trough, and they are directed horizon- 

 tally, and as tangents, to the mean circumference, between that 

 of the trough and of the drum. The velocity which the water 

 has acquired by its fall along these pipes makes the machine 

 move round its axis ; and this motion accelerates, by degrees, 

 till the velocity of the water in the space between the trough 

 and drum equals that of the water from the reservoir: so that no 

 sensible shock is perceived of the affluent water upon that which 

 is contained in the machine. 



This circular motion communicates to the water between the 

 trough and drum a centrifugal force, in consequence of which 

 it presses against the sides of the trough. This centrifugal force 

 acts equally upon the water contained in the compartments at 

 the bottom of the trough, but it acts less and less as this water 

 approaches the centre. 



The whole water, then, is animated by two forces, which 

 oppose each other ; namely, gravity and the centrifugal force. 

 The first tends to make the water run out at the hole at the 

 bottom of the trough; the second tends to drive the water from 

 that hole. 



To these two forces are joined a third, namely, friction, which 

 acts here an important and singular part, as it promotes the 

 efficacy of the machine, while in other machines it always dimi- 

 nishes that efficacy. Here, on the contrary, the effect would 

 be nothing, were it not for the friction, which acts in a tangent 

 to the sides of the trough and the drum. 



By the combination of these three forces, there ought to 

 result a more or less rapid flow from the hole at the bottom of 

 the trough : and the less force the water has as it issues out, the 

 more it will have employed in moving the machine, and of 

 course in producing the useful effect for which it is destined. 



The moving power is the weight of the water running in, 

 multiplied by the height of the reservoir from whicli it Hows 

 above the bottom of the trough : and the useful effect is, the 

 same product, diminished by half the force which the water 

 retains when it issues out of the orifice below. 



We endeavoured to ascertain by a direct experiment the 

 amount of this useful effect. We fixed a cord to the axis of the 

 machine, which by means of pulleys properly placed raised a 

 weight in proportion as the machine turned round. The result 

 of repeated experiments was, that the effect produced amounted 

 to -jv of the moving cause, and often approached -Vo» even not 

 reckoning the friction of the pulleys, &c. which has nothing to 

 do with the machine. This effect surpasses considerably that of 

 the best machines known. 



Hence this new piece of mechanism, notwithstanding its 



