200 SIR DAVID GILL. 



Meanwhile, with the sanction of the Admiralty, a new 

 meridian circle had been constructed and erected in a specially 

 designed house, in accordance with plans prepared by Gill. Much 

 time was spent on preliminary investigations of the instrument 

 before it was brought into regular use in 1905. Though no defini- 

 tive results with this instrument were obtained during Gill's 

 directorate, subsequent discussion of the observations have served 

 to prove that it has in a large measure realised the high expecta- 

 tions that he had fomied. 



The munificent gift to the Observatory of a large refractor of 

 24-in aperture, fully equipped for the most refined spectroscopic 

 researches, by Mr. Frank McClean in the year 1897, served to 

 open up new fields of research, into which he threw himself with 

 characteristic energy. 



One of the earliest objects to which it was devoted was to 

 the confirmation of Mr. McClean's own discovery of the presence 

 of oxygen in certain of the fixed stars, but Gill's greater interest 

 lay in the application of the spectroscopic method to the refined 

 measurement of velocities in the line of sight. Such determina- 

 tions, if carried out on a sufficiently extensive scale, might be 

 expected to throw light on the great cosmical question of the 

 stellar distributions. Moreover, even in the early days of the use 

 of the method he had foreseen the possibility of utilising it for 

 a determination of the dimensions of the solar system with an 

 accuracy at least comparable to that with which it had been 

 derived from even the best previous methods. A large number of 

 photographs of spectra with this oliject in view were obtained 

 during his tenure of office. These have been subsequently dis- 

 cussed and a value of the solar parallax derived in almost perfect 

 accord with that obtained by Gill in previous methods. 



Early in his career at the Cape, Gill succeeded in impressing 

 on the Colonial authorities the urgent desirability of an accurate 

 survey of the country. Thanks to his persistent advocacy and 

 tact in securing the co-operation of the various authorities con- 

 cerned. South Africa has now been covered with a network of 

 primary triangulation extending from Cape Agulhas to within a 

 few miles of Lake Tanganyika, of an accuracy which bears fav- 

 ourable comparison with any similar system in the world. Most of 

 this has been accomplished under Gill's directorship. It was his 

 ambition to see the chain carried throughout the continent so as 

 to connect up with the surveys in Egypt and thence ultimately 

 with the great European surveys. 



Vast as was the work accomplished cither personally by Gill 

 or under his immediate directorship during his career at the 

 Observatory, he always had time to spare to help on projects for 

 the advancement of science. He was early elected to the presi- 

 dency of the South African Philosophical Society, which was 

 founded shortly before his arrival in the Colony, and always took 

 a deep interest in its work. When the foundation of the South 



