207 
THE CENTENARY OF THE DISCOVERY OF 
URANUS. 
By W. F. DENNING, F.K.A.S. 
T HE year 1781 was signalized by an astronomical discovery 
of great importance, and one which marked the epoch as 
memorable in the annals of science. A musician at Bath, 
William Herschel by name, who had been constructing some 
excellent telescopes, and making a systematic survey of the 
heavens, observed an object on the night of March 13 of that 
year, which ultimately proved to be a large planet revolving 
in an orbit exterior to that of Saturn. The discovery was 
as unique as it was significant. Only five planets, in addition 
to the Earth, had hitherto been known ; they were observed by 
the ancients, and by each succeeding generation ; but now a 
new light burst upon men. The genius of Herschel had singled 
out from the host of stars which his telescope revealed, an 
object, the true character of which had evaded human 
perception for thousands of years ! 
The centenary of this remarkable advance in knowledge 
naturally recalls to mind the circumstances of the discovery, and 
makes us inquisitive to know what new facts have been gleaned 
of Herschel’ s planet now that a hundred years have passed away 
and we are enabled to look back and review the vast amount of 
labour which has been accomplished in this wide and attractive 
field of astronomical research. We may learn what new fea- 
tures have been discerned of the new body, and what additional 
discoveries in connexion with other planets, unknown in 
Herschel’ s day, have been effected by aid of the powerful tele- 
scopes which have been devoted to the work. We do not, how- 
ever, intend dealing with the general question of planetary 
discovery, for at a glance we are impressed with its magnitude. 
While a century ago five planets only were known, we now 
have some 230 of these bodies, and the stream of discovery 
flows on without abatement through each succeeding year. 
