F 14
Clocks. The performance of the Sidereal Clock, Dent 39741, has again been characterized by a steady increase in losing rate since April. It varied from -0s.35 on April 11th and 12th (Barometer 30in.05 Temperature 60°.8) to +0s.30 on December 26th (Barometer 30in.08 and temperature 66°.1).
Sidereal clock Cottingham and Mercer, No. 507, has been in use as the Observatory Standard since March 10.
The clock was adjusted on several occasions during the year and the contact springs cleaned on July 20. From November 11 to December 31 the clock was undisturbed and its daily losing rate varied from +0s.04 to 0s.07; the greater part of this variation is due to changes of pressure in the clock case brought about by changes of temperature in the room.
In the following table is given the excess of the observed error of the Sidereal Standard Clock over the computed error during cloudy periods in 1925:
Date 1925Interval without observationsExcess of observed over computed error (secs.) January 919+ 0.42 212+ 0.56 218 days+ 0.90 29 February 1420+ 0.28 3+ 0.29 11+ 0.47 3+ 0.45 26 April 1127+ 0.26 17+ 0.11 3+ 0.24 252+ 0.16 + 0.01 May 313 7 2 + 0.01 June 1825 July19- 0.05 August13 September 2+ 0.20 November 1835+ 0.16 + 0.02 + 0.08 December 20+ 0.13 25- 0.19 212+ 0.06 243+ 0.09 4+ 0.09 272+ 0.02 + 0.02The large errors of the clock on January 19-21 have already been alluded to under "Timeball"; otherwise a very considerable improvement has been effected in the Time Service generally, by...