1888.] Determination of the Viscosity of Water. 131 



Also log 10 = 0-81151 log R = 1-06354 



logrj = 0-53705 log 6 = 2-19229 



1-34856 3-25583 



= 3-25583 



2-09273 



log^ = 2-52092 

 



4-61365 



Multiplying by 57'3 

 to convert to 

 circular measure 



log 57-3 = 1-75815 





2-37180 

 Whence K = 0-02354. 



The diagrams, which were taken at random from many similar ones 

 plotted during the course of the experiments, give A at the tempera- 

 tures at 4, 13-8, and 48 C. 



We have A 4 = 0'0582. 



A 13 . 8 = 0-0458. 



A 48 = 0-023. 



Also since K = 0'02354, 



r 2 = 5-017, 



h = 11-07, 



r 2 - ri = 0-381, 



we have ^H!il = 2-606 x 10~ 5 , 



Z'TTT^n 



whence ^ = 15-166x10-7, 



Ai 18 . 8 = 11-93 . . . ., 

 ;, 48 = 5-99 . . . . 



The results are shown in the form of a curve in Diagram 2, the 

 ordinates being the values of yu T and the abscissas the temperature. 



Poiseuille's results are shown by the dotted curve. 



The chief interest of these experiments, beyond that attaching to 

 an independent determination of fi by a new method, lies in the com- 

 paratively high velocities at which the viscous forces remain the 

 principal cause of resistance. 



VOL. JT v. K 



