of the Sun and Solar Sxflctn . 249 
fuch as are neared: to us; and, therefore, their influence on 
our Situation would alone prove a powerful argument in favour 
of the proper motion of the fun, had it actually been origi- 
nally at reft. But I (hall wave every view of this fubjccf 
which is not chiefly derived from experience. 
To begin with my own, 1 will give a Ihort but general ac- 
count of the mod: ftriking changes l have found to have hap- 
pened in the heavens lince flamstead’s time, i have now 
almoft fmifhed my third review. The firft was made with a 
Newtonian telefcope, fomething lefs than 7 feet focal length, 
a power of 222, and an aperture of 4! inches. It extended 
only to the ftars of the firft, fecond, third, and fourth mag- 
nitudes. Of my lecond review 1 have already given lome ac- 
count ^ : it was made with an inftrument much fuperior to 
the former, of 85,2 inches focus, 6,2 inches aperture, and 
power 227. It extended to all the ftars in Harris's maps, 
and the telefcopic ones near them, as far as the eighth magni- 
tude. The catalogue of double ftars, which I have had the 
honour of communicating to the Royal Society, and the dis- 
covery of the Georgium Sidus, were the refult of that review. 
My third review was with the fame inftrument and aperture, 
but with a very diftind power of 460, which I had already 
experienced to be much fuperior to 227, in detecting exceftively 
fmall ftars, and fuch as are very clofe to large ones. At 
the fame time I had ready at hand fmaller powers to be 
uled occafionally after any particularity had been obferved 
with the higher powers, in order to fee the different ef- 
fects of the feveral degrees of magnifying fuch ob- 
jects. I had alio 18 higher magnifiers, which gave me a 
gradual variety of powers from 460 to upwards of 6000, 
in order to purfue particular objeds to the full extent of 
* Phil, Tranf. vol. LXX; LXXI. •LXXII. 
