292 



REPORT 1893. 



1| inch from front to back. One of the screw-feet is placed due east of 

 the axis of the pendulum, and the line joining the other two is therefore 

 north and soutli. The lower half of the front contains a circular window, 



Fig. 2. 



o 



1 



4 inch in diameter, thi'ough which the pendulum-mirror is visible. 

 This box is only a little larger than the mirror, and is connected above 

 with a brass tube, c, If inch in external diameter and 12| inches high, 



