si 6 Dr. Herschel's Observations on 
coma ; and this, it may be supposed, must render the measure 
less satisfactory than it would otherwise have been. 
From these data we compute, that the disk appeared to the 
natural eye under an angle of 3' 14/', 33; while Ceres, when 
magnified 516^ times, was seen by the other eye of an equal 
magnitude ; and that consequently its real diameter, by mea- 
surement, was only o",38. 
April 22. 11 h 38', sidereal time. I used now a more perfect 
small mirror ; the former one having been injured by long con- 
tinued solar observations. This gave me the apparent diameters 
of the stars uncommonly well defined ; to which, perhaps, the 
very favourable and undisturbed clearness of the atmosphere 
might contribute considerably. 
With a magnifying power of 881,51, properly ascertained, 
like those which have been mentioned before, I viewed Dr. 
Olbers’s star, and compared it with a lucid disk of 1,4, inch in 
diameter, placed at 1514 inches from the eye, measured, like 
the rest of the distances, with long deal rods. The star appeared 
to me so ill defined, that, ascribing it to the eye-glass, I thought 
it not adviseable to compare the object, as it then appeared, 
with a well defined lucid disk. Exchanging the glass for that 
which gives the telescope a magnifying power of 51 I found 
Pallas, as the discoverer wishes to have it called, better defined ; 
and saw, when brought together, that it was considerably less 
in diameter than the lucid disk. 
In order to produce an equality, I removed the disk to 1942 
inches ; and still found Pallas considerably less than the disk. 
Before I changed the distance again, I wished to ascertain 
whether Ceres or Pallas would appear under the largest angle, 
especially as the air was now more pure than last night. On 
