2 Mr. Herschei/s and Mr. South’s observations of the apparent 
of celestial observations) and the progress we may yet hope 
for from farther improvements in this respect, there is every 
reason to suppose it still the most eligible mode of setting at 
rest that great question, and to believe that no distant period 
must put us in possession of something decisive from this 
quarter, as to the existence or non-existence of an appreciable 
amount of that element. 
Meanwhile unexpected phaenomena have been witnessed. 
The existence of binary systems, in which two stars perform 
to each other the offices of sun and planet, has been distinctly 
proved, and the periods of rotation of more than one such 
pair ascertained with something approaching to exactness. 
The immersions and emersions of stars behind each other 
have been noted, and real motions among them detected, 
rapid enough to become sensible and measureable in very 
short intervals of time. 
The results of Sir William Herschel’s observations from 
1779 to 1784, were published in two Catalogues in the Phi- 
losophical Transactions for 1782 and 1785, and consist of 
descriptions and measures of 702 double and triple stars. 
The labour of re-examination was undertaken and executed 
by him in 1801, 2, 3 and 4, after a lapse of twenty years ; and 
the changes observed or suspected in them were recorded in 
two other papers, published in the volumes for 1802 and 1804. 
It was to be naturally expected that, owing to the imperfec- 
tion of the micrometers with which many of the earlier mea- 
sures, especially those of 1 779 and 1780, were performed, 
and the novelty of the subject, many errors would have crept 
in ; and that a verification of the facts, by farther observation, 
would at all events be highly desirable. Accordingly, in the 
