DEPARTMENT OF MERIDIAN ASTROMETRY. I29 



use of the instrument, to the improvements introduced, and to the successive 

 and laborious efforts made to correct its indications for unavoidable errors 

 of construction or action. 



During the year a clock of precision by Clemens Riefler, of Munich, has 

 been purchased and set up in order to increase, if possible, the precision of 

 the right-ascensions determined with the transit-circle, especially as to 

 periodic errors that may be induced by diurnal change of atmospheric press- 

 ure and temperature. This form of clock has a nickel-steel pendulum in an 

 air-tight case exhausted to a partial vacuum. 



In general, preparation for the proposed observations in the southern 

 hemisphere have been continued, but at present these do not appear to require 

 any special comment. 



