590 



SCIENCE. 



[N. S. Vol. XII. No. 303. 



ADDRESS OF THE CHAIE3IAN OF THE DE- 

 PARTMENT OF ASTRONOMY OF THE 

 BRITISH ASSOCIATION. 

 It has been decided to form a Depart- 

 ment of Astronomy under Section A, and I 

 have been requested to give an address on 

 the occasion. In looking up the records of 

 the British Association to see what position 

 astronomy has occupied, I was delighted 

 to find, in the very first volume, ' A Eeport 

 on the Progress of Astronomy during the 

 Present Century,' made by the late Sir 

 George Airy, so many years our Astrono- 

 mer Royal, and at that time Plumian Pro- 

 fessor of Astronomy at Cambridge. This 

 report, made at the second meeting of the 

 Association, describes, in a most interest- 

 ing manner, the progress that was made dur- 

 ing the first third of the century, and we 

 can gather from it the state of astronomical 

 matters at that time. The thought natur- 

 ally occurred to me to give a report, on 

 the same lines, to the end of this century, 

 but a little consideration showed that it was 

 impossible in the limited time at my dis- 

 posal to give more than a bare outline of the 

 progress made. 



At the time this report was written we 

 may say, in a general way, that the 

 astronomy of that day concerned itself with 

 the position of the heavenly bodies only, 

 and, except for the greater precision of ob- 

 servation resulting from better instruments 

 and the larger number of observatories at 

 work, this, the gravitational side of astron- 

 omy, remains much as it was in Airy's 

 time. 



What has been aptly called the New or 

 Physical Astronomy did not th^en exist. I 

 propose to briefly compare the state of things 

 then existing with the present state of the 

 science, without dealing very particularly 

 with the various causes operating to pro- 

 duce the change ; to allude briefly to the 

 new astronomy ; and to speak rather fully 

 about astronomical instruments generally, 



and of the lines on which it is most prob- 

 able future developments will be made. 



In this report * we find that at the be- 

 ginning of the century the Greenwich Ob- 

 servatory was the only one in which ob- 

 servations were made on a regular system. 

 The thirty -six stars, selected by Dr. Maske- 

 lyne, and the sun and moon were observed 

 on the meridian with great regularity, the 

 planets very rarely and only at particular 

 parts of their orbits ; small stars, or stars 

 not included in the thirty-six, were seldom 

 observed. 



This state of affairs was no doubt greatly 

 improved at the epoch of the report, but it 

 contrasts strongly with the present work at 

 Greenwich, where 5,000 stars were ob- 

 served in 1899, in addition to the astro- 

 graphic, spectroscopic, magnetic, meteoro- 

 logical and other work. 



Many observatories, of great importance 

 since, were about that time founded, those 

 at Cambridge, Cape of Good Hope, and 

 Paramatta having just been started. A 

 list is given of the public observatories then 

 existing, with the remark that the author 

 is ' unaware that there is any public ob- 

 servatory in America, though there are,' 

 he says, ' some able observers.' 



The progress made since then is truly re- 

 markable. The first public observatory in 

 America was founded about the middle of 

 the century, and now public and private 

 observatories number about 150, while the 

 instrumental equipment is in many cases 

 superior to that of any other country. The 

 prophetic opinion of Airy about American 

 observers has been fully borne out. The 

 discovery of two satellites to Mars by Hall 

 in 1877, of a fifth satellite to Jupiter by 

 Barnard in 1892, and the discovery of 

 Hyperion by Bond, simultaneously with 

 Lassall, in 1848, are notable achievements. 



The enormous amount of work turned 

 out by the Harvard Observatory and its 



* Brit. Assoc. Report, 1831-32, p. 125. 



