F 11
The number of observations in the years 1918 and 1919 were as follows
Transits,
Level determination,
Azimuth
Collimation
*}
""
1918. 1919.
1,522 1,321
787 676
23 23
22 99
No transits of the Sun were utilized during 1919.
The azimuth and collimation determinations were made by the Chief and First Assistants from observations of the old south mark.
Clocks. The losing rate of the Standard Sidereal clock, Dent No. 39741, varied from -0.12 sec. on February 5 (Barometer 30ins. 33 Temperature 55°.6) to -0.55 sec. on August 7 (Barometer 29ins. 48 Temperature 86°).
The rate during cloudy periods was usually derived from the formula:-
−0·792 + 0·575 (b−29ins.) + 0·00021 (t−50°) where r is the computed losing rate, and b and t the mean barometric pressure and temperature, respectively, for the preceding 24 hours.
In the following table is given the excess of the observed over the computed error after cloudy periods during 1919 :--
Date 1919. Interval without observations. Excess of observed over computed error. January + days 3 secs. + 0.28 11, 10 + 0·64 15, 5 0.36 29. 3 0.16 "" 77 0.80 February +0'14 5 5 + 0·09 27 3 Ο ΟΙ 0*39 >> 15 + 0·50 "" 7 0*24 March 24, 0'41 18, 5 0'00 IO 3 0.28 17 ― 0*08 "" 0'31 25, 5 "" April 4, 9 + 0.59 19, 3 0'09 9 3 0:04 " 17 0'57 " 3 O'12 May "" June July August >> >> 3 + 0.40 October 5 041 1) 4 C'00 November 4 + 0.02 10, 20, December 17. 9 26, 1, 18, 6. 29, 12. 24, 29, 16. 229 3, 4 19 " 13, 6 "" 2Page 165
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