ASTRONOMICAL OBSERVATIONS. 223 
I know that the celebrated Englith aftronomer Halley, 
was the firft who, about the year 1719, by a careful com- 
parifon of the obfervations of Flamftead with thofe of 
Ptolemy, refpeGting a few fixed ftars, viz. Sirtus, Arturus 
and Aldebaran, difcovered that thefe ftars had a proper 
motion of their own. But IJ likewife know, that in Flam- 
ftead’s Britith celeftial hiftory the word concomitant or at- 
tendant of fixed flars is made ufe of, when that great man 
had not even thought of a proper motion of the fixed ftars. 
The other aftronomers, pofterior to Halley, as far as 
they inveftigated the proper motion of the fixed fars, fol- 
lowed the Italian method of comparing their own obfer- 
vations with thofe of the ancients. This method requires 
the labour of prolix calculation, and remains liable to 
doubts and uncertainty, on account of the inaccuracy of 
ancient inftruments and obfervations. My new method 
is not liable to fuch obje@tionsy becaufe from the obferved 
variation of the attendant ftar and the brighter fixed flar, 
it immediately follows that there is a proper motion giv- 
en, either of the one or the other. 
I have, therefore, in the fpace of two years, obferved 
almoft two hundred attendants of different fixed ftars, 
running almoft the fame parallel, immediately before 
or after the fixed ftar; and have communicated many 
of fuch obfervations to the celebrated Englith aftronomer 
Nevil Mafkelyne, who has expreffed his high fatisfaQion 
therewith. 
Out of many obfervations, I fend your illuftrious foci-~ 
ety a few by way of {pecimen, being fuch whereof I find 
correfpondent obfervations in the Flamfteadian celeftial 
hiftory ; whence it appears at once how excellently ob- 
fervations of this kind ferve for difcovering the proper mo- 
tion of fuch ftars. 
The firft and fecond column of the following table next 
to the left hand is eafily uriderftood from its title. The 
third column fhews the difference of A. R, in mean time 
Ei 2 between © 
