distances and positions of 380 double and triple stars , &c. 3 
year 1816, a second re-examination of the measures was en- 
tered on by his Son (one of the authors of this paper), and 
some progress made in it ; several of the results of which 
will be found attached to the measures in the following pages. 
The instruments in Mr. South’s possession being peculiarly 
adapted to the purpose, a similar idea had also occurred to 
him ; and, at his suggestion, it was determined to undertake 
the work of re-examination in concert, which was accordingly 
commenced in March, 1821, and continued, whenever weather 
and circumstances would permit, till the present time. 
Meanwhile (though at that time unknown to us), a similar 
undertaking had been commenced and carried to a consider- 
able extent by a very exact and assiduous continental astro- 
nomer, Mr. Struve, Director of the Imperial Observatory of 
Dorpat. The comparison of his observations of such of our 
stars as have been measured by him with our own, will not 
be found the least interesting part of the present paper. So 
far as it goes, the coincidences of our results, with very few 
exceptions, are striking ; and afford the most satisfactory 
ground for reliance on the methods employed by both. 
Professor Amici, of Modena, has also of late occupied him- 
self in the pursuit of the same object, with instruments said 
to be of extraordinary power. Very few, however, of his 
results have come to our knowledge, and those imperfectly 
stated ; hence it may fairly be presumed that the differences 
existing between them and our own, will be found to admit 
of easy explanation. 
The instruments employed in our combined observations, 
are two capital achromatic telescopes mounted equatorially, 
of the respective focal lengths of five and seven feet. These 
