114 
CELESTIAL DAY OBSERVATIONS. 
Observations 
upon fixed 
Stars in die 
day-time. 
the stars Bellatrix, Orion's Girdle, a Androraedae, a Pegasi, 
Aieoth, Benetriach, North brown, and several other stars of the 
3d magnitude. 
All the above stated observations, as well as those which 
follow, were made with the 20-inch telescope (unless other- 
wise stated) and in every instance the sun was shining bright. 
From the above, and similar observations made on the fixed 
stars, the following conclusions are deduced, 
T. That a magnifying power of 30 times is sufficient for 
distinguishing a fixed star of the 1st magnitude, even at noon 
d.ay, at any season of the year ; provided it have a moderate 
degree of elevation above the horizon, and be not within 30® 
or 40® of the sun’s body. Also, that, by a magnifying power 
of 15, a star of this class may be distinguished, when the sun is 
not above an hour aud a half above the horizon. Butin every 
case higher powers are to be preferred. Powers of 45 and 60 , 
particularly the last, were found to answer best in most cases, as 
with such powers the eye could fix on the star with ease as soon 
as it entered the field of the telescope, 
2, That most of the stars of the 2d magnitude may be seen 
with a power of 60 when the sun is not much more than 2 hours 
above the horizon ; and at any time of the day, the brightest 
stars of this class may be seen with a power of 100 when the 
sky is serene, and the star not too near the quarter in which the 
sun appears. 
3. ' That in every instance, an increase- of magnifying power, 
has the principal effect in rendering a star easily perceptible, — 
That diminution of aperture, in most cases, produces a very 
slight effect, in some cases none at all, and when the aperture 
is contracted beyond a certain limit, it produces a hurtful effect. 
The cases in which a moderate contraction is useful,are the tw’O 
following : 1 , When the star appears in a bright part of the 
sky, not far from that quarter in which the sun appears, 2, 
When an object glass of a large aperture* and a small degree of 
magnifying power are used. In almost every instance the con- 
traction of the object glass of the 8-inch telescope, with a power 
45, had a hurtful effect. But when the 20-inch telescope 
carried 
