660 HEPOUT— 1900. 



many yeara our Astronomer Royal, and at that time Plumiah Professor of 

 Astronomy at Cambridge. This report, made at the second meeting of the 

 Association, describes, in a most interesting manner, the progress that was made 

 during the first third of the century, and we can gather from it the state of 

 astronomical matters at that time. The thought naturally 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 disposal to give more 

 than a bare outline ol' 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 witli tlie position of the heavenly bodies ' 

 only, and, except for the greater precision of observation resulting from better 

 instruments and the larger number of observatories at work, this, the gravitational 

 side of astronomy, remains much as it was in Airy's time. 



What has been aptiy called the New or Physical Astronomy did not then 

 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 produce 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 probable future developments will be made. 



In this report ' we find that at the beginning of the century the Greenwich 

 Observatory was the only one in which observations were made on a regular 

 system. The thirty-six stars selected by Dr. Maskelyne, aad the sun and moon, 

 were observed on the meridian with great regularity, the planets vei-y 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 aflairs 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 observed in 1899, in addition to the aatrographic, spectroscopic, magnetic, 

 meteorological, 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 observatory iu America, though there 

 are,' he says, ' some able observers.' 



The progress made since then is truly remarkable. The first public observa- 

 tory in America was founded about the middle of the century, and n)w public 

 and private observatories number about 150, while the instrumental equipment ia 

 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 1S77, of a fifth satellite to Jupiter by Barnard iu 

 1892, and the discovery of Hyperion by Bond, simultaneously with Lassell, iu 

 1848, are notable achievements. 



The enormous amount of work turned out by the Harvard Observatory and its 

 branches in South America, all the photographic and spectroscopic work carried 

 out by many difl'erent astronomers, and the new lines of research initiated show 

 an amount of enthusiasm not excelled by any other country. A greater portion 

 of the astronomical work iu America has been on the lines of the new astronomy, 

 but the old astronomy has not been at all neglected. In this branch pace has 

 been kept with other countries. 



From this report we gath(>r that the mural quadrant at most of the observa- 

 tories v/as about to be replaced by the divided circle. Troughton had perfected a 

 method of dividing circles, which, as the author says, ' may be considered as 

 the greatest improvement ever made in the art of institiment making.' 



Two refractors of 11 and 12 inches aperture had just been imported into 

 this country; clockwork for driving had been applied to the Dorpat and Paris 

 e^uatorials, but the author had not seen either iu a state of action. 



The m-thod of mounting iustrumeuta adopted by the Germans was rather 



» Brit. Assoc, Report, \^'M-22, p. 125. 



