312 the president's address. 



partially aside, can hardly realize the popular feelings associated 

 with this science in the minds of enthusiastic beginners.* 



The progress of astronomical science during the last fifty 

 years has been so great, that I have had some hesitation in 

 deciding what branch I should select as the principal theme of 

 my address. If I had chosen what may be termed the mathe- 

 matical section of astronomy, or the theories of the movements 

 of the various members of the solar system, I should have been 

 able to have shown you how, by the nightly labours of the 

 faithful planet-watchers at Greenwich, the peculiar motions of 

 the sun, moon, and planets, from Mercury to Neptune, and the 

 effects of their mutual attraction on each other, have been 

 determined with an accuracy that leaves but little room for any 

 further improvement in their calculated orbits. For it must be 

 claimed for our National Observatory, that its reputation is 

 second to none among the observatories of the world, and that 

 every standard lunar or planetary theory investigated by English 

 or foreign mathematicians, has been based on the meridian 

 observations of the sun, moon, and planets made at the Royal 

 Observatory, Greenwich. I could also have given you some 

 slight idea of the daily work carried on within the walls of an 

 astronomical observatory, which even to this day is a source of 

 mystery to many. But, as I have said, I would rather speak of 

 a comparatively new branch of astronomy which, although its 

 details may appear somewhat technical to a general assembly, is 

 deserving of the greatest consideration by all who are interested 

 in the progress of knowledge. This branch of the physics of 

 astronomy is now permanently added to the daily routine work 

 of the Eoyal Observatory, side by side with the old-established 



* The following extract is taken from a paper read at a recent meeting of the 

 Eoyal Astronomical Society. It gives a good illustration of the kind of night- 

 exposure to which astronomers are sometimes liable. Mr. Boeddicker, astronomer 

 at the Earl of Rosse's observatory, who has been engaged more than five years 

 on an elaborate drawing of the Milky Way, states : — As much as possible I drew 

 the different sections only when they were near the meridian, in order to obtain 

 the conditions most favourable for atmospheric transparency. This involved for 

 the greater part of the Milky Way the necessity of my lying flat on my back (or 

 nearly so) in the open air for hours together — a position which, especially on 

 frosty nights, proved somewhat trying, for no amount of clothing was found 

 sufficient to counteract the radiation of heat from the body. 



