HYDRAULICS. 



31 



own axis, which it does with very little 

 friction. Towards the lower extremity 



fig 22. 



of the pipe v u, and at right angles to 

 its axis, two or more smaller pipes or 

 arms with closed external ends are in- 

 serted, as at z a, and an adjustable ori- 

 fice is made at the side of each of these 

 small pipes as near as possible to its 

 end, and placed on opposite sides of 

 such pipes, so that water issuing from 

 them may spout horizontally and in op- 

 posite directions, as shown at the letters 

 z and a. One end of a pipe b commu- 

 nicates with a supply of water which it 

 delivers into the funnel head i\ without 

 touching it in any part, and the supply 

 of this pipe must be so regulated by a 

 cock or otherwise, that it may con- 

 stantly keep the pipe u v filled with 

 water without running over, at the same 

 time that the discharge is goins: on from 

 the orifices z a, which will deliver their 

 water with a force proportionate to the 

 perpendicular height of the column of 

 water contained in u v : and since the 

 holes z a are in opposite directions, the 

 water in passing from them will gene- 

 rate such a resistance or re-action 

 as to throw the pipe u r, with its 

 arms and axis x, into rapid rotatoiy 

 motion, and this axis may communi- 

 cate its motion and power to wheel- 

 work or machinery, or even to a mill- 



stone connected with its upper end. This 

 machine is described and highly spoken 

 of in almost all the books that treat of 

 hydraulic machinery, but it does not ap- 

 pear to have been carried into practical 

 effect in England. Euler enters into an 

 elaborate description of the theory and 

 importance of this machine in the me- 

 moirs of the Academy of Berlin for 1 751 , 

 and agrees with Bernouilli, at the close 

 of his Hydraulics, in saying that it excels 

 all other methods of employing the force 

 of water to obtain motion. *The power of 

 this machine does not depend altogether 

 on the perpendicular height of the water 

 in the pipe u v, but on the centrifugal 

 force that is generated in the arms z a, 

 by which a much more rapid and vio- 

 lent discharge of the water takes place 

 than would occur from the elevation of 

 head alone, and by which a propor- 

 tionate velocity of motion is also pro- 

 duced. In Rozier's Journal de Physique, 

 August 1775, there is an account of an 

 improvement of this machine by M. 

 Mathon de la Cour, in which the water 

 is made to ascend instead of descend into 

 the pipe u v, by means of a close ground 

 joint : in this way any height of water 

 can be conducted by close pipes to ope- 

 rate on the machine without increasing 

 the height and consequent weight of the 

 revolving pipe, which makes the ma- 

 chine much more compact and free from 

 friction. Mr. Waring describes a ma- 

 chine of this description, on M. Mathon 

 de la Cour's construction, from his own 

 inspection, in the 3d vol. of the Trans- 

 actions of the American Philosophical 

 Society, and of which he gives the fol- 

 lowing dimensions. The radius of the 

 arms from the centre pivot to the centre 

 of the discharging holes forty-six inches ; 

 inside diameter of the arms three 

 inches ; diameter of the supplying pipe 

 two inches ; height of the working head 

 of water twenty-one feet above the points 

 of discharge. This, though a great fall, 

 is evidently a very small consumption of 

 water, since it was all supplied by a 

 two -inch pipe ; and when the machine 

 was not loaded, and had but one dis- 

 charging orifice open, it made 115 turns 

 in a minute. This gives a velocity of 

 forty- six feet in a second for the orifice 

 of discharge, which is nine feet and 

 five-sixths in a second faster than the 

 water would flow out under the simple 

 pressure of a twenty-one feet head, 

 which great excess of velocity can only 

 be attributed to the prodigious centri- 

 fugal force generated in the arms, and 



