Dear Sir, The method, which I mentioned to you when I was last in London, by which it might perhaps be possible to ind the distance, magnitude, and weight of some of the fixed stars, by means of the diminution of the velocity of their light, occurred to me soon after i wrote what is mentioned by Dr. Priestley in his History of optics, concerning the diminution of the velocity of light in consequence of the attraction of the sun; but the extreme difficulty, and perhaps impossibility, of procuring the other data necessary for this purpose appeared to be to be such objections against the scheme, when I first thought of it, that I gave it them no farther consideration. As some late observations, however, begin to give us a little more chance of procuring some at least of these date, I thought it would not be amiss, that astronomers should be apprized of the method, I propose (which, as far as I know, has not been suggested by any one else) left, for want of being aware of the use, which may be made of them, they should neglect to make the proper observations, when in their power; I shall therefore beg the favour of you to present the following paper on this subject to the Royal Society.