\02 '^"E WATER RAM, 



Marhine of Thc machine of Marly, when first constructed, appears ta 



Marly. j-j^^^g produced ~ of the powcr expended, so that ^ of 



its power were (chiefly) misapplied. This misapplied power 



ha:; been injurious to it, and the wear it has occasioned has re* 



duccd the cflcct to ^%, -g-^, and at length even to -s^o.* 



HydrauTic ma- It Avould be difficult to exhibit the results of other similar 



rai io>o9-ioti)s hydraulic machines with wheels and pumps, becau'se they arc 



of their power, not common, and arc often erected under circumstances 



where it is not easy to make the proper calculations ; but it is 



certain that, with all possible care in the execution, they 



usually produce less than one-tenth of the power employed. 



They are not very productive therefore ; but this .is not th» 



"Why tJiey are only reason for their being so rare. In fact thcy^are Tiot ap-^ 



mou"'^"' *'■'''"' plicable to a number of foils of water, small in quantity, of, of 



little height; and their cxpcnce includes not only the cost of 



the machinery, but of buildingri to defend it from the weather,. 



which renders them very costly. 



The effect of A wafer ram, made uith cc.ve, may produce -yV-^ of its 



the water r;:m first power, as I have seen : but in wneral it gives only ■j%'^r» 



equal to 3-4ths ^ /, , , , CO ■ I T L T .. 



t)f its power, Indeed i engage only lor -^^-q or ^ : I mean, that it you would 



and at least ^. Yr^y^ water by it 10.0 feet with a fall of 5, only a fortieth part 

 of what falls will be rai!'ed <to that height. If the fall \yerc 10 

 feet, a twentieth part of the water would be raised : if the.' 

 height were 200 feet, and thc fall 5, only an eightieth part; 

 and so in all other ca^cs. 



I shall hereafter relate thc e>:perimcnls from which I 

 deduce these results. 

 Superiority of Thus we mii^' admit, that thc waier ram generally gives -^^^ 

 the water ram. ^f the power it expends. Its cft'ect therefore is five times as 

 much as that of the common hydraulic machines, under the 

 same circumstances ; yet it is far from being perfect, as *ji- 

 pears from the rules I have laid down forjudging of the mt'rits 

 vi a machine. It may be rendered more etiective, as I have* 



* The part of the Seine that passes the machine at Marly is neap- 

 ly equal to 200,000 cubic inches, and falls about four feet and half. 

 The inovinu; power therefore is 300,000 + 4"5=r: 1,350,000. Ihe 

 quantity of water raised was 120 hydraulic inches, and the licight 

 475 feet. Thc power produced therefore was 120-t-'175=o?,000, 

 or _5^ of that rtpcnded. 



already 



