in the relative Situation of Double Stars, &c. 363 
On looking over the 4th column of this table, it will be found, 
that the differences between the observed and calculated angles 
are not greater than may be expected, considering that most of 
the early measures are single, and cannot have the accuracy 
which may be obtained by repetition. Even as they are, we 
must acknowledge them sufficient to ascertain the gradual 
change in the angle of position of the two stars. In one 
place, the difference amounts to six degrees ; but it will soon 
appear, that a more accurate annual motion gives a calculated 
position which takes off much of the error of this measure. 
In a conversation with my highly esteemed friend the Astro- 
nomer Royal, he happened some time ago accidentally to 
mention, that Dr. Bradley had formerly observed the two stars 
of a Geminorum to stand in the same direction with Castor and 
Pollux. It occurred to me immediately, that if the time of this 
observation could be nearly ascertained, it would be of the 
greatest importance to the subject at present under consideration. 
For, should Dr. Bradley’s position be very different from a 
calculated one, it would induce us at once to give up the idea 
of a revolving star. The observation was made by Dr. Bradley 
with a view to see whether any change could be perceived in 
the course of the year, by which the annual parallax of the stars 
might be discovered. Dr. Maskelyne, who had this informa- 
tion from Dr. Bradley in conversation, had made a memoran- 
dum of it in his papers. He has been so kind as to look for 
it; and, as soon as he found the note, he sent me the following 
copy, which I have his permission to transcribe. 
“ Double star Castor . No change of position in the two Stars ; 
“ the line joining them , at all times of the year, parallel to the line 
