Astronomical Soczety. 295 
presses it) opened the Great Book of Nature, and explored 
that vast and splendid Volume, as the best Catalogue that he 
could find for the occasion. At the time that he began his 
important and interesting enquiries, he was not aware of more 
than four stars that came under the description of double 
stars: yet, with this small stock he began his pursuit; and, in 
the course of a few years, formed a catalogue of 269 double 
and triple stars, which he presented to the Royal Society, and 
which is published in the Philosophical Transactions for 1782. 
‘In this Memoir, and in all his subsequent ones, he gave not only 
the Distances between the two stars, as measured by various 
methods, but also the Angle of Position, or the angle formed 
by the parallel of declination, and an imaginary line joining 
the two stars. These records have now become of conside- 
rable importance, as enabling future observers to compare their 
results, and thus determine the change which those quantities 
have undergone during the interval that has elapsed since they 
were made. 
Ever ardent in the cause of science, this distinguished astro- 
nomer followed up his favourite pursuit by a second collection, 
consisting of 434 additional double stars; which was published 
in the Philosophical Transactions for 1785. : 
In the years 1803 and 1804: he communicated to the Royal 
Society “ An account of the changes that have happened 
during the last 25 years, in the relative situation of double 
stars :” and it was in these papers that he first made known 
to the world those astonishing and important facts which have 
so justly excited the admiration of astronomers. In order to 
set this in a clearer light, I would remark that it had been 
hitherto a commonly received opinion, that the difference in 
the apparent magnitude of the fixed stars was caused by the 
difference in their distance from the eye of the observer : that 
a star of the first magnitude, for instance, was situated nearer 
to us than one of’ the second magnitude; and this again, 
nearer to us than one of the third magnitude; and so on in 
succession till we came to the smallest point visible in the most 
powerful telescopes : and moreover that those apparent com- 
binations of stars, by twos or by threes, or any larger clusters 
(numbers of which present themselves to the eye of the ob- 
server) were merely the consequence of their lying nearly in 
the same line of vision, and that they were nevertheless se- 
parated from each other by an immense and immeasurable 
distance. But this, however much it may be true in some par- 
ticular instances, is not universally the case: for, in the course 
of the observations alluded to in the two papers just men- 
tioned, the most remarkable and unexpected pheenomena pre~ 
sented 
