xvi President's Address 



scrutiny to which the heavens are now subjected 

 by the large number of excellent telescopes in the 

 hands of private observers and enthusiastic amateur 

 astronomers, especially in England and the United States. 

 Small comets are probably far more numerous than 

 we suppose, as at the brightest part of their apparition 

 many are only just visible in telescopes of large dimensions, 

 and would escape detection altogether were it not for the 

 almost competitive watchfulness of such observers. Perhaps 

 the most noteworthy item of astronomical progress during 

 the past year has been in the application of photography for 

 mapping the stars. Some experiments in that direction at 

 the Paris Observatory and elsewhere are full of promise, and 

 photographic charts obtained of some rich celestial areas 

 show that every star^ down to magnitudes far smaller than 

 can be seen by the naked eye, are faithfully depicted in 

 their true relative positions on the sensitive plate ; while 

 it is found that some stars are photograplied which, on 

 account of their peculiar light, have not been hitherto 

 detected in the telescope. At present, however, there are 

 certain physical and mechanical difficulties which render all 

 the pictures comparatively unsatisfactory. Long exposure 

 is necessary, during which atmospheric changes often occur, 

 and it appears at present, mechanically, almost impossible to 

 secure such equable motion of the photographic telescope as 

 is requisite to keep the image of a star on the same exact 

 spot of a sensitive plate for an hour or more at a time. If 

 greater chemical rapidity of the sensitive film, and a truly 

 uniform motion of the telescopes, can be obtained — things 

 we do not think quite impossible — photography promises 

 great things for astronomy in the future. 



As regards our Observatory, we have not much to re- 

 cord for the past year ; it has been occupied, as usual, with 

 its utilitarian work of star-cataloguing, search for, and 

 revision of known nebula, observations of comets dis- 

 covered, as well as its accustomed work in meteorology and 

 terrestrial magnetism. A commencement has been made in 



