Report of combined meeting of Commissions 8 (Meridian Astronomy), 19 (Variation Of Latitude) and 31 (Time), August 21. 9.30 a.m

Extract

The President outlined the history of the Ross photographic zenith tube, saying that it was originally designed for measurement of the variation of latitude by Dr Ross, and later adapted to the determination of time by Dr Littel. The success of the instrument and its possible application to various problems in positional astronomy made it of interest to all three commissions attending the combined meeting.

Dr Schilt said that the zenith tube could not determine fundamental positions, but that it could determine fundamental proper motions in declination with a high degree of accuracy.