214 
Transactions of the Boyal Society of South Africa. 
Six photographs were taken — October 19th, October 20th, October 21st, 
November 7th, November 13th, November 14th. 
Prints of these are l)efore me as I write, and when one compares this 
first impoverished venture with the magnificent pictures of the sky now 
turned out nightly at every standard observatory, one is stirred at the 
thought of the clear vision and great faith of David Gill as he looked upon 
the little print, 3i- inches by 2, and saw in it the promise of a great future. 
In the first photograph, that of October 19th, the comet was followed, 
and the stars were left to trail, Gill's desn-e being to obtain a picture of 
the comet. In the second photograph, that of October 20th, the comet 
w^as left to trail : a single circumstance had changed his whole outlook. 
His desire now was to obtain pictures of stars. 
In the succeeding star photographs, November 7th and November 14th, 
he increased the exposure from one houi- to one and a half hours, and 
finally to two hours, obtaining on his last picture ten times as many stars 
as he did on the first. 
The writer has, as one of his most cherished possessions, the first 
rough draft of the letter Gill sent home telling of his success, and urging 
the employment of photography in securing and defining star places and 
magnitudes. The letter reads :— 
" These photographs appear to have a far-reaching interest from the 
fact that notwithstanding the small optical power of the instrument with 
which they were obtained, they show^ so many stars, and these so well 
defined over so large an area as to suggest the practicability of employing 
similar but more powerful means for the construction of star maps on any 
required scale and to any required order of magnitude." 
The original six plates are now in the possession of the Eoyal Astro- 
nomical Society, and the small lens with which they were taken in that 
of the Eoyal Observatory at Cape Town. 
In November of the same year Gill wrote to Dallemeyer requesting 
him to send a lens suitable for photographic work. In reply there 
was sent out to the Cape a rapid rectilinear lens of 6 inches aperture 
and 54 inches focal length. 
At the same time also he sent a paper expressing his views on astro- 
graphic photography to Admiral Mouchez, director of the Paris Observa- 
tory, for presentation to the French Academy of Sciences. So strongly 
did Gill's letters, papers, and drawings impress Mouchez w^ith the possi- 
bilities of stellar photography, that he urged the brothers Henry to devote 
their whole energies to the new mode of research. This they did, with 
what brilliant success we all know. 
In 1884 Gill went home to England, and while there he did his best to 
further the idea of a Southern Photographic Durchmusterung. 
The Royal Society placed an annual grant of £300 at his disposal, and 
