Observations with Katers Pendulums. 169 



In which, 



B= Observed reading of Barometer - 0*022 and reduced 



to 32° Fahr. 

 7"= Mean Temperature of the Pendulum during the 



swing. 

 a and b. — The observed Arc of Vibration in inches at 



the commencement, and at the end. 

 D, d, and r. — The distances of the Arc Scale from the 



observing telescope, tail piece and knife edge 



respectively. It was adopted for the three pen- 



Hence, 



Arc correction = 0-13/(a + (^)- — J(a — /^)-) 



And if V= number of vibrations in a mean solar day i^educed 

 to 62° Fahr., 26 inches pressure and infinitely small arc, we 



0/3 



have F=7? — "^ -f a + /3 + T. This is the formula used in the 

 reductions. 



The general results are given in the following tables : Note — 

 A full account of these operations will appear in the publications 

 of the Melbourne Observatory. 



