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around the spindle, due to the friction of the bearing, is met in this way: 
At nine inches from the center of the yoke, and on the line of knife edges 
for weights, is an inverted knife edge (f). Above this a sensitive scale 
{e) is suspended and a link connection is made between the scale and the 
knife edge. The tendency of the yoke to revolve is met by the pull of the 
seale and the amount of the pull is registered on the scale. 
Variation in speed is arranged for by placing on the end of the spindle 
that passes through the yoke a cone pulley of four steps (g), and this is 
driven by a belt from a corresponding cone pulley on a shaft (h) in the 
lower part of the frame. On this shaft is another cone pulley of three 
steps (j) driven from one on a countershaft. So a wide range of speeds 
can be gotten, and from a countershaft driven at 300 turns in a minute 
the spindle in the yoke has been made to revolve at speeds varying from 
thirty turns in a minute to 9,000 turns in a minute. 
On the assumption that in some forms of bearings the suspension of 
thé yoke on the spindle would be from some point near the top of the bear- 
ing, a yoke was made in which the knife edges for the weight rods could 
be raised and lowered, and some tests were made on different types of 
bearings with the edges at places above and below the center of the yoke; 
but though the suspension varied from the top to the bottom of the spindle 
no measureable change could be found. 
To overcome the difficulty of finding the zero point for any test, a 
slightly greater weight was given to the scale side of the yoke than to the 
other side; and any one reading was made by driving the spindle first in 
one direction and then in the other, as this would give the amount of pull 
due to friction on the scale, as from the point found when driving one way 
to the corresponding point found when driving the other would be twice 
the amount that would be gotten when driving in either way alone. 
Tue TorpLter-Houtz MacHINE For RoENTGEN Rays. 
By J. L. CAMPBELL. 
