R. M. Beeley — The Viscosity of Ice. 



267 



Experiment No. 2. 



X = 



A, day; B, hour of day; C, temperature at time of observation; D, mean 

 temperature ; E, length of test bar in millimetres ; F, mean hourly extension 

 in hundredths of a millimetre ; G, stress in kilos, per square centimetre ; 

 H, viscosity. 



Defining the ' coefficient ' of viscous traction as 



/ 



dv 



dx ■ 



when X is the coefficient, / the force (tractive or tensile) per unit 

 area, and v the velocity at any point x, we have, for cases where the 

 applied force / is so great in comparison with the weight of the bar 

 that the latter may he neglected 



where v is the rate of extension of a rod of length x. 



It has been shown by Trouton that ' the coefficient of viscosity ' is 

 equal to one-third of the ' coefficient of viscous traction '.^ 



Applying the above to the first experiment of Dr. Maiu, given in 

 Table I, we have 



/= 2-7 kilos per cm. ^ 



= 2700 X 980-5 dyn. per cm.^ 

 X = 235 mm. 



V = 00268 mm. per hour. 

 = 0-0268 -:- 60^ mm. per see. 

 . ^ _ 2700 X 980-5 x 235 x 60^ 

 0-0268 

 = 83-5 X 10'- 



1 Proc. Eoy. Soc, A, vol. Ixxvii. 



