Section A. 

 ASTRONOMY, MATHEMATICS, AND PHYSICS. 



ADDRESS BY THE PRESIDENT, 

 H. C. RUSSELL, B.A., C.M.G., F.R.S., 



Government Astronomer, Sydney. 



THE PROGRESS OF ASTRONOMICAL PHOTOGRAPHY. 



Our section embraces a wide range of subjects, and the honorable 

 position in which you have placed me to-day gives me a recognised 

 right to select a theme for my address from any of these subjects, 

 and to treat it in one of two ways — either to endeavor to add some- 

 thing of my own to the present sum of knowledge, or to endeavor 

 to pass in review what has been done. My impression is that the 

 latter is the better course, and I hope you will be able to agree 

 with me. 



I will confine my remarks to a branch of one of our subjects 

 which, within the past twenty years, has done more than any- 

 thing else to accelerate the progress of our knowledge and to extend 

 our grasp of the grand truths of astronomy. I refer, of course, to 

 the application of photography to the wants of astronomical 

 research. Coming in at first as another possible aid to the observer, 

 it has already shown us that in many cases the observer must stand 

 aside while the sensitive photographic plate takes his place and 

 works with a power of which he is not capable ; and 1 feel sure that 

 in a very few years the observer will be displaced altogether, while 

 his duty will be done by a new sensitive being, not only taking in 

 the visu.al ray, but also the actinic rays into ultra violet — a being 

 not subject to fatigue, to indigestion, to east winds, to temper, and 

 to bias, but one, above all these weaknesses, calm and unruffled, 

 Avith all the world shut out, and living only to catch the fleeting 

 rays of light and tell their story. 



It has been well said by a very gifted writer' that "the invention 

 of the telescope itself does not mark an epoch more distinctly than 

 the admission of the camera to the celestial armory. All the con- 

 ditions of sidereal research in especial are being rapidly transformed 

 by its co-operation." 



By this new lever the progress of astronomy is being urged for- 

 ward at a rate which accomplishes more in ten years than was 



