igS SIR DAVID GILL. 



than the comet itself was the number and perfection of the star 

 images found to be impressed on the plate. The images were 

 such that their positions could be easily measured with high pre- 

 cision. Here then was a means by which the stars throughout the 

 sky could be rapidly charted. Moreover by regulating the time of 

 exposure the pictures could be made to indicate any desired limit 

 of stellar magnitude. Correspondence with Admiral Mouchez, 

 the Director of the Paris Observatory, was at once opened, the 

 outcome of which was the formation of an International Com- 

 mittee of xA.stronomers, which iirst met in Paris in 1S87, to discuss 

 the project of obtaining photographs on a uniform plan of the 

 whole sky. 



But without waiting for the deliberations of this Com- 

 mittee, (jill set to work to make a preliminary survey of the 

 Southern skies. With the aid of grants from the Government 

 Grant Fund of the Royal Society, and partly at his own expense, 

 a series of photographs covering the whole region of the sky from 

 18° S. declination to the South Pole was secured during the 

 years 1885-1889. 



At first it seemed probable that the measurement and discus- 

 sion of these plates would have to be relegated to a remote future, 

 but thanks to a timely offer of co-operation from Kapteyn, of 

 Groningen, arrangements were made by which all the plates were 

 sent to Holland and measured there. The results of this happy col- 

 laboration are contalined in three volumes of the Cape annals under 

 the title of the Caf^e Photograpliic Diirchmustrnnu/. whereby 

 the visual " Durchmusterungs " of Argelander and Schonfeld 

 are extended to the South Pole. 



The work has pro\-ed in\alua])le as a contril)Ution to statis- 

 tical enquiries regarding the distribution of stars of different 

 magnitudes in the sky, and as affording ]M"eliminary rough data to 

 form the basis of a more accurate survey. 



Meanwhile, in April, 1887, the Paris Conference had met and 

 plans had been agreed on whereby the larger scheme of photo- 

 graphing the whole sky on a scale of i millimetre to a minute of 

 arc was divided up among eighteen co-operating observatories, 

 the largest share being apportioned to the Cape. Regular work on 

 this programme was begun at the Observatory in 1892, and has 

 continued to the present time. The pul:)lication of results, which 

 will be contained in eleven volumes, giving the accurate positions 

 in duplicate of about half a million stars, is however now in pro- 

 gress, and Gill had the satisfaction- of seeing the issue of the first 

 of these volumes shortly before his death. 



The general organisation of this scheme was controlled by 

 the Paris Committee, which met again on various occasions 

 l>etvveen 1889 and 1909. At each of these meetings Gill was 

 present, and his voice was prominent in guiding the course of pro- 

 cedure. His vigorous presence and directing influence at such 

 meetinus will be sorelv missed in the future. 



