110 
CELESTIAL DAY OBSERVATIONS. 
Telescope 
)fU4de ute of. 
Jones, Holborn, London, The telescope, which originally || 
accompanied the insirumenf, was an achromatic refractor, its j 
object glass being 8 1 inches focal distance, and one inch dia- -I 
meter, carrying a magnifying power of seven times It was 
afterwards furnished with an eye-piece, which produced a raag-« 
nifying power of 45 times, which' it bore with great distinct- 
ness. With this telescope and the power last mentioned, seve- 
ral of the observations were made. But (he greater number 
were made with an achromatic telescope, having its object glass 
20 inches focus, and about l|- incli diameter, which was after- 
wards attached to the equatorial machinery in place of the 
small telescope above-mentioned. , It'was furnislied with mag- 
nifying powersof 15, 30,45,60, and 100 times. The in- 
strument was fixed in a position nearly fronting the south ; but 
could occasionally be removed to another position fronting the 
north-west. 
The observations were began about the end of August, 
1812, and were continued, as opportunity offered, to the same 
period in 1 81 3. The latitude of the place of observation is 
about 56° 30' north. The particular observations stated, are 
' taken from memorandums noted at the time of observation. 
Observations on fixed Stars of the f rsl Magnitude. 
. April 23d, 1813. lOh, 15'A. M. the sun being 54 hours 
Obse'‘vations ' 
upon fixed above the horizon, S.rw the star Vega, or a Lyrae, very dis- 
tinctly with a power of 30 times. Having contracted the 
aperture of the object glass to nine-tenths of an inch, saw it 
on a darker ground, but not more plainly than before. Having 
contracted the aperture still farther, to half an inch, I perceived 
the star, but not so distinctly as before. Tlie sky being very 
clear, and the star in a quarter of the heavens nearly op[)osite 
to the sun, I diminished the magnifying power to 15, and 
could still perceive the star, but indistinctly ; it was just per- 
ceptible. April 22d. Saw Aldebaran at ih. 40' P. M. very 
distinctly with a power of 60 j the aperture not diminished. 
Same day, at 2h, 15' P. M. saw Beteigeux, or a Orionis, with a 
power of 60, and immediately afterwards with a power of 30 ; 
th« 
