F 
Py 
4 
4 
2 
. 
3 
ie 
3 
4 
A 
H 
é 
A 
4 
H 
‘Eanes 
No 

The several parts have the following dimensions. The 
wire is of tempered steel 0.2 millimeter in diameter and 110 
centimeters long. The disc is of lead 12.6 centimeters in 
diameter and about 0.5 cm. thick, mounted in the middle 
of a brass axis 15. cm. long, and weighs, with its axis and 
resistance cylinder 1150 gms. The moment of inertia of 
the disc with the resistance cylinder attached is about 
2,000,000,000 mgr. mm? and its time of oscillation 35 sec- 
onds. . 
he resistance cylinder is made from a piece of brass 
tubing 6.4 cm. in diameter and 5 cm. long, and is supported 
by a stiff wire which is connected to the axis of the disc by 
asmall set screw so that it may be- readily removed for 
cleaning. 
FeThe liquid to be tested is placed in a beaker, or other 
suitable vessel, which should be large enough to allow at 
least two centimeters between its sides and the revolving 
cylinder. The same vessel with which the apparatus is 
calibrated should be used in all cases. The revolving disc 
should be inclosed to protect it from currents of air, which 
have a decided influence upon the result. 
