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therefore, that, on our hypothecs, any ftar muft 
have a different apparent place for every different 
colour ; that is, its apparent difk muft be drawn out 
by the aberration into a longitudinal form, refem- 
bling the prifmatic fpedtrum, having its red ex- 
tremity neareft its mean place. In the ftars fitu- 
ated about the pole of the ecliptic, its length 
fliould continue always the fame, tho’ directed along 
all the different fecondaries of the ecliptic in the 
courfe of a year : but in thofe which lie in or near 
the plane of the ecliptic, it ftiould be greateft at the 
limits of the eaftern and weftern aberrations, the ftar 
recovering its colour and figure, when the true and 
mean places coincide. But there is no hope of dif- 
covering, whether our fyftem be true or falfe, by 
this confequence of it : for the greateft length of the 
dilated difk being to the whole aberration, as the dif- 
ference of the velocity of the red and violet to the 
mean velocity of light, i. e. but about a 77th part 
of it, cannot much exceed the fourth part of a fecond. 
11. The time which the extreme violet light takes 
in arriving from any diftance to the eye, will be to 
that which the extreme red takes in coming from 
the fame, as 78 to 77. If Jupiter be fuppofed in a 
quadrate afpedt with the fun, in which pofition the 
eclipfes of his fatellites are moft commodioufly ob« 
ferved, his diftance from the earth being nearly equal 
to his diftance from the fun, light takes about 41' in 
pafling from him to the earth ; therefore the laft 
fenfible violet-light, which the fatellite refledls before 
its total immerfion into Jupiter’s fhadow, ought to 
continue to affedt the eye for a 77th of 41' 5 that is, 
about 3 2" of time after the laft fenfible red light is 
gone. It is therefore a certain confequence of our 
L 1 2 hypothefis. 
