1888.] 



Determination of the Viscosity of Water. 



127 



a remontoir weight in connexion with a governor, and the speed 

 recorded electrically on a chronograph by means of a contact maker 

 on the axis E. 



The torsion of the wire C was measured on a divided circle H, 

 attached to B. 



To get the absolute value of the torsion-scale the following method 

 was used : 



W (fig. 2) is a small weight hung at the end of a silk thread S in 

 the neighbourhood of the torsion- wire C. H is the divided circle on 

 B. From S a second thread, L, is taken to the circumference of H. 

 The point of W is over a horizontal scale, and a reading of its position 

 taken when there is no strain on L, that is, when S is hanging verti- 

 cally. The weight W is then displaced by unclamping the circle H 

 from B and winding up the thread L round its circumference, then 

 reclamping H and allowing things to come to rest ; readings are then 

 taken of the displacement of W and the position of H. After this 

 the thread L is cut and the position of H read again. 



