The weather being as favourable as possible, I saw with 415,7 the globule No. 10 round at first sight; the magnified angle is 1' 5l",2. I can see No. 12 steadily round; the angle is 0",172. It is however a mere point, and divisions of it cannot be made.
With a new 10-feet reflector, power 540, the globule No. 10 is beautifully well defined, and 12 of it may be estimated; the angle is 0",268; 12 of it is 0",l34.
With the old reflector, and 502,6, I see No. 12 steadily round. No. 7, 11, and 13, have met with an accident, and could not be observed.
6th Experiment with illuminated Globules.
The night being very dark, 8 silver globules, from ,0291 to ,00596 in diameter were placed on the post, and illuminated by a lantern held up against them.
With 522,7 I saw them all perfectly well, but the small quantity of light thrown on them was not sufficient to make angular experiments upon them. As objects I saw them as easily as in the day time. Probably the phases of the illuminated disks I saw might be such as the moon would show when about 9 or 10 days old. The angle of No. 8, had it been full, would have been 0",519. A better way of illumination might be contrived.
SPURIOUS DIAMETERS OF CELESTIAL OBJECTS.
Observations and Experiments, with Remarks.
July 17, 1779. With a 7-feet reflector, power 280, I saw the body of Arcturus, very round and well defined. I saw
