Description of a New Compensating Pendulum. 275 
formity of action ina time-keeper. The arrangement of the parts 
is so simple as to be readily understood by any skillful workman, 
and as it is entirely free for the adoption of any one who may 
prefer its construction, I have prepared a description and diagram 
to render it intelligible. 
Fig. 1, shows the whole pendulum, the 
dotted lines representing similar parts to those 
on the opposite side, and are introduced to 
render the drawing more easily understood ; 
@ isa similar spring to that which is attached 
to the pendulum of an ordinary eight-day 
clock, and is firmly attached to the perpen- 
dicular brass bar 6. Through 6b there is the 
usual opening for the guy-wire, which gives 
motion to the pendulum. This bar is firmly 
affixed to the transverse bar ¢ either by riv- 
eting or soldering. On each end of the bar c 
there is attached a brass rod d, d, and one inch 
from each of these there is also affixed a steel 
rod c,e. These four rods pass through the bar - 
P, which is intended merely to preserve them ~ 
in their proper position, and is attached:to the 
two brass rods by a pin passing through both, 
while the steel rods are allowed to move 
freely through the holes. At_f, a transverse 
bar or lever is affixed tod by a loose pin pass- 
ing through them, and the same attachment 
is made to the steel rod eat g. This bar is 
four inches long, three inches of which ex- 
tend from g to A, and a similar one is at- 
tached to the dotted rod d and extends on 
the opposite side. At A there is another loose attachment to the 
rod 7, which is of steel, and which is again affixed to the bar k. 
At & there is a permanent bar m, which passes through the weight 
0, and has the usual adjusting screw 2 at the bottom. 
Rationale.—Suppose that by au increased temperature of 20°, 
the steel rods e, e, are expanded in length j, of aninch. The 
rods d, d, being of brass, and a small fraction larger than the steel, 
will expand ¢ of an inch by the same increase of temperature, 
it being an established theory with the best French chemists, 
Fig. 1. 
