884 SIR DAVID GILL. 



of his work on the Mauritius and Ascension expeditions was the chief 

 factor leading to his selection as Her Majesty's Astronomer at the 

 Cape of Good Hope, in the year 1879. The Cape Observatory had 

 enjoyed an honorable history, dating back to 1820, and the traditions 

 as to its most profitable fields of actiA'ity were well developed. Gill 

 accepted these traditions as a guiding principle, but his ability as an 

 observer, his mechanical skill in designing practicable instruments of 

 greater power and accuracy, and his enthusiasm and energy gave new 

 life to the institution, and in a few years it was in the front rank of 

 existing observatories. His administration was marked by a great 

 expansion of financial and personal resources ; 1)3' the development 

 of the heliometer method of determining solar parallax and stellar 

 parallaxes; by marked advances in our knowledge of the distances of 

 the Sun and the brightest stars; by more accurate and more extensive 

 observations of stellar positions, with improved meridian instruments; 

 by a photographic durchmusterung of the southern sky between 

 declination -18° and the South Pole, which made available the approxi- 

 mate positions of 400,000 stars, a work in which Professor Kapteyn 

 collal)orated heroically; by the inaugiu'ation of spectrographic ob- 

 servations for determining the radical velocities of the southern stars; 

 by a splendid determination of the solar parallax from the radial 

 velocities of certain stars; and by many other contributions in in- 

 struments, methods and results which lack of space prevents us from 

 describing. 



Gill's influence was not confined to the Cape Observatory. It was 

 one of the chief factors in inaugurating and carrying forward the 

 International Photographic Catalogue plans, which involve the 

 laborious charting of the entire sky by photography, on the scale of 

 1 mm. to one minute of arc, by many observatories. 



In no direction were Gill's technical and administrative ability and 

 his personal influence more potent and wise than in the plans for 

 the Geodetic Survey of South Africa. The political aspects of the 

 problem were not simple, for his plans related to a comprehensive 

 system of triangulation extending over several independent states. 

 The physical difficulties resulting from climatic and other conditions 

 were formidable. In no continent have the plans for geodetic surveys 

 been conceived and carried out with higher standards. 



A long list of honors came to Gill in recognition of his services to his 

 country and to science. He was created Companion of the Bath in 

 1896, and Knight Commander in 1900. He was appointed a Com- 

 mander of the Legion of Honor (France) in 1908, and a Knight of the 



