66 Mr. wilson’s propofed Experiment by 
fame manner it may be Shewn, that at any other time the par- 
ticle will be found in the interfeCtion : it, therefore, from the 
time of its direction being changed at B, muft pafs relatively 
along the moving line as before. By a fmall alteration in the 
conStruCtion it may be (hewn, that if the abfolute path had 
been fo changed at B as to have augmented the angle FBD, Still 
the particle would have moved relatively along DB, provided its 
velocity after had been to its velocity before as the fine of FBD 
the firit angle to the fine of the increaled angle. 
To apply, therefore, this proposition to the prefent investi- 
gation, let DB be conceived as the axis of a telefcope perpen- 
dicular to. the Spherical furface of a refracting medium which 
accompanies it in its lateral motion, SB the abfolute path ot a 
particle of light which had pafifed relatively along DB pro- 
duced, till its. arrival at B, and Blv its abfolute path within the 
medium of the telefcope. Then it is evident, that FBD, or its 
equal CBS, will be univerfally the angle of incidence, and 
RBD the angle of refra&ion. Hence, by prop. A. that ray 
of the parallel pencil which is refraCted at O, the vertex ot 
the lpherical furface in fig. 2. muft Still pafs relatively along the 
axis, provided the velocity within the telelcope be to its former 
in air, as the fine of incidence to the fine of refraction. But 
the image of the ftar being produced by the meeting of all the 
contemporary light, will confequently be found in the axis,, 
which, by hypothefis, deviates from the true place of the Star 
by the fame quantity as Dr. Bradley’s angle; So that in this 
way of considering the matter, the fame thing relults which 
was formerly Shewn in regard to a telefcope fo conStruCted. 
By prop. A. it is alfo manifest, that whatever number of re- 
fractions that ray which falls upon the extremity of the axis 
Suffers in pervading objeCt-glaffes of any figure, or even denfe 
media. 
