433 
of some of the principal fixed Stars , &c. 
The errors of simple division alone are those which continued 
observations have no tendency to diminish ; these, by making 
the microscopes revolve, may be completely done away. An 
instrument thus constructed would be well adapted to detect 
small motions in the fixed stars which hitherto have escaped 
notice, or such as are but imperfectly known ; for we cannot 
reasonably conclude that what is termed the proper motion 
of a star is so uniform and constant, that being once deter- 
mined, it will remain always the same. 
In the following observations, the larger number expresses 
the altitude, -J- go°, and the smaller number the zenith dis- 
tance ; the thermometer was attached to the telescope. 
In reducing the observations of 1801, the proper motions are 
allowed for, according to the latest tables of Dr. Maskelyne* 
