Page:Philosophical Transactions - Volume 095.djvu/51

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of ascertaining the Magnitude of small celestial Bodies.

see a celestial body under the same angle, I could never mis- take it for a small star. The angle it subtends is 0",999.

I see the diameters of No. 2 and 3 very clearly, and can divide them by estimation into two parts, half of No. 3 is 0",311.

I see No. 4 and 5 as round bodies, but cannot divide them by estimation. The diameter of No. 5 is 0",45. No. 6 may also be seen, but 7 and 8 are invisible.

These objects reflecting too little light, the silver globules of the 3d experiment were placed on the tree. It will be right to mention that they were all so far tarnished by having been out in the open air for more than a fortnight, that no improper reflection was to be apprehended.

The air being uncommonly clear, I saw with 502,6 the globules No. 1 , 2, 3, 4, 5, and 6, as well defined black balls. I could easily distinguish 1/4 of the diameter of No. 6; which is 0",139.

With 415,7 I saw them all round as far as No. 10 included.

With 502,6 Isaw No. 9 and 10 very sharp and black, and could divide No. 10 into two parts, each of which would be 0",134.

With a new lens, power 759,7, I saw No. 10 better than with 502,6, and could with ease distinguish it into halves, or even third parts of its diameter, 1/2 of it is 0",089.

With 223,1 I saw them all as far as No. 10 included as visible objects, but the smallest of them were mere points. No. 6 might be divided with this power into two parts; each being 0",279.

With 292,1 I saw No. 10 sharp and round. The magnified angle is only 1' 18",3. One half of No. 6 may be perceived with great ease.