1885. 



NEW YORK ACADEMY OF SCIENCES. 



103 



The fluid passing along the pipes between A and B, and 

 through the pumps, will lose, each second, a certain amount of 

 head per unit of weight, because of the resistances. 



Let K equal this resistance. Then we can say : 



The loeight of fluid per second is then di7'ectlij 'proportional to 

 the effective head, and inversely proportional to the resistance. 

 This is Ohm's law, which, for electricity, is : The iiitensity of 

 the current is directly proportional to the difference of potential 

 and inversely as the resistance. 



The loss of power, per second, in friction in the pipes, is the 

 loss of head multiplied by the weight per second. This is Joule's 

 law for loss in heat for electricity: 



EI = ^i^), RP = 



R 



r_e[E-e] 

 R 



Work jier second of pump A=Headxwt. per second. 



E(E-e) 

 R 



(E-e)= 



EI 



lost in pipe A B = rR: 



R 



1= 



R=head lost j)er unit of weight per second. 

 E-e Weight j diff. head \ Ohm' 



H 



R pel' second— ] head lost per unit of wt. per second- 1 law. 



Work lost per second = I (E-e) = ^-5^^= PR (Joule's law). 

 Work per second of motor B = head x wt. per second. 



el 



e(E-e) 



R 



Theoretical Efficiency = ^=- 



