TOL. LIX.] . PHILOSOPHICAL TRANSACTIONS. 619 



Fig. 7 represents the appearance of the salts in hemp-seed, after a month's infusion, from the 25th 

 of February to the 25th of March, in New-river water. 



Fig. 8 the salts, about a month after, April '25, appeared in this manner. 



Fig. 9. these figures represent them about the 5th of May, or 10 days after. 



Fig. 10, about the 20th of May, they exhibited the figure of precious stones. 



Fig. 1 1, these Mr. E. called seminal salts, as these small figures are to be seen in most of the in- 

 fusions, rising at diflferent times, and exhibiting these shapes, when they first appear distinctly. 



Fig. 12 represents the salts of hemp-seed in distilled water, that had been infused from the 30lh 

 of April to the 1 2th of May. 



Fig. 13 shows the form of the salts when the putrefaction had begun to separate their parts into 

 lamin2e in the distilled water. 



Fig. 14 are the figures of the salts that appeared from the hemp-seed, infused in hard pump-water 

 about 12 days, from the 5th of May to the 17th. 



XIX. On the Computation of the Suns Distance from the Earth, by the Theory 

 of Gravity. By the Rev. Mr. Horsley, F. R. S. p. 153. 

 A little treiitise, that has lately been published, against Dr. Stewart's method 

 of determining the distance of the sun by the theory of gravity, has put me on 

 reconsidering a subject which had been long dismissed from my thoughts. I am 

 far from being convinced that Dr. Stewart's conclusions are " erroneous on his 

 own principles," as his antagonist affirms; and I am well satisfied that there is no 

 error in the principles themselves. I have always been sensible that an extreme 

 precision was requisite in determining the mean quantity of the solar force affect- 

 ing the moon's gravity towards the earth, in order to obtain an accurate estima- 

 tion of the distance; and this circumstance was mentioned by me in a paper that 

 I communicated to the Society about 1 years ago,* before it had been remarked, 

 that I knew of, by any other writer on the subject. I must now declare, that 

 the imperfection of the method arising from this circumstance is much greater 

 than I was at first aware of. I owe this better information entirely to the revisal 

 of Dr. Stewart's Theorems, not to any thing that has been written on the sub- 

 ject by others. I find that if I increase the mean quantity of the sun's disturb- 

 ing force, as determined by Dr. Stewart in the gth proposition of his Supple- 

 mental Tract, and by myself, in my former paper, by ^ ^^^^ part of itself, I 

 obtain, by my own method of compututation, 9" 3"'.3Q4 for the sun's mean 

 horizontal parallax; which seems to be so nearly the mean of the quantities of 

 the parallax deduced from the best observations of the transit of 1761, that it 

 would be ridiculous to set up, any longer, the conclusions of this theory in op- 

 position to observation. It is much more probable that the theory should err in 

 so small a matter as , ^^^q of the sun's disturbing force, than that observation 

 should err in more than 4., thai is nearly in 4- of the whole quantity in question. 

 I beg the favour of you to communicate this to the Society. 



• See Phikjs, Trans., vol. 57i pp. 179, 183. Or these Abridgments, vol. 12, p. 41 1, Sec. 



4 K 2 



