562 Philosophical Transactions of the 
The second paper is also by the same author, and contains an ac- 
eount of a microscopic doublet. Adopting the principle employed in 
the form of the eye piece used in telescopes, and called Huygenian, 
he forms his magnifier of two plano-convex lenses. This plan he in- 
ferred would obviate both the spheric and chromatic aberration, and 
prodvée a much more distinct image than has yet been attained in 
any other manner. These anticipated advantages were fully real- 
ized in -practice, and he states that he was enabled, by the aid 
of a microscope constructed upon this principle, to view the most 
minute objects, with ‘a degree of delicate perspicuity he had in vain 
sought invany other microscope with which he was acquainted.” 
The next\of Wollaston’s papers contains an account of a method of 
comparing ‘the light-of the sun with that of the fixed stars. It is 
founded upon'a suggestion of the Rev. John Mitchell, published:as 
jong since as towards the close of the last century, but which was rude 
and imperfect in the hands of the inventor, and has not been since used 
by any other person. The distance of the fixed stars is a problem the 
‘solution of which has escaped the ordinary direct modes of investiga- 
tion,’ The search after their annual parallax led at first to the dis- 
covery of other and far more important irregularities by which it is 
cloaked ; and the best instruments, that the present state of the arts 
has supplied, have left the question, whether it is of such magnitude 
as to be detected or not, unsettled. Pond, observing with the two 
magnificent murals of the Greenwich observatory, conceives that this 
parallax is imperceptible, while Brinkley, an astronomer not less ac- 
tive and zealous, but furnished with less perfect instruments, thinks 
that he has detected it. In the absence of this direct method, the 
proportion which the light, afforded to us separately by each of the 
fixed stars, bears to the light of the sun, furnishes the best, and perhaps 
the only method within our reach, of obtaining a probable estimate of 
their distances. ‘The manner in which this principle was applied by 
Wollaston, will be best explained by quoting his own words : 
»/ From a comparison which 1 made in’ the year 1799, of the light 
of the sun with that of the moon; I should estimate the direct light of 
the sun, as being nearly one million times greater than that of the 
moon; and consequently, the direct light of the sun as very many 
million times greater than that afforded by all the fixed stars collect- 
ively» Such then being, to our visual organs, the vast disproportion 
in radiance between the sun and the whole starry firmament, it is not 
expected that we should assign: very accurately how much 
"greater the ihe of the sun is than that exceedingly minute quantity 
