[ 19 ] 
IV . — On a method of comparing the light of the sun with that of the fixed stars. 
By William Hyde Wollaston, M.D. F.R.S. 
Read December 11, 1828. 
ONE of the most ingenious contributors to the Transactions of our Society 
in the last century, the Rev. John Michell, in a paper intituled “ An inquiry 
into the probable parallax and magnitude of fixed stars, See*.” has proposed it 
to astronomers, as an object worthy their attention, to determine what propor- 
tion the light, afforded us separately by each fixed star, bears to the light 
which we receive from the sun ; since, from our inability to measure the annual 
parallax of those very remote bodies, such a comparison is the best, perhaps 
the only method within our reach, of obtaining, though not certain, yet pro- 
bable estimates of their distances ; and thus forming reasonable conjectures 
concerning the extent of the visible universe. In order that we may judge, 
with the least chance of error, of the mean distance of those stars which are 
the nearest to the earth, he directs us to compare the light of the brightest 
stars with that of the sun, and next to calculate how far the sun must be re- 
moved, to make the light that we should then receive from him, not more than 
equal to the mean light of the stars chosen for comparison. 
Mr. Michell made, as he says, some rude experiments for determining the 
comparative brilliancy of certain principal stars ; but has not suggested any con- 
trivance for comparing a star with the sun. He states, however, so distinctly the 
great object of such a comparison, and the inferences which an industrious ob- 
server would thence be entitled to draw, concerning the distances of those stars 
whose light he might succeed in measuring, that it is surprising that no astrono- 
mer has been incited by these remarks to devise a method of making the requisite 
observations, and that now, so many years after Mr. Michell’s suggestion was 
made public, so much remains to be effected in this branch of photometry. 
* Phil. Trans. 1767 : p. 234. 
D 2 
