Astronomy. 
drant of eight feet radius, constructed by 
Bird, in 1750, he made an immense num- 
ber of observations, for settling the places 
of all the stars in the British catalogue, to- 
gether with nearly 150 places of the moon, 
the greater part of which he compared with 
Mayer’s tables. 
Dr. Bradley was succeeded in 1762, in 
his office of astronomer royal, by Mr. Bliss, 
but who, being in a declining state of health, 
died in 1765, and w'as succeeded by Ne- 
vil Maskelyne, D. D., the present astrono- 
mer royal, who has rendered considerable 
services to this science, by his publication 
of the “Nautical Almanac,” the “Requi- 
site Tables,” &c. ; and more particularly 
by the great assiduity and zeal he has dis- 
played in bringing the lunar method of de- 
termining the longitude at sea into general 
practice. 
Such was the state of astronomy, when 
Dr. Herschell, by augmenting the powers 
of telescopes beyond the most sanguine ex- 
pectations, opened a scene altogether un- 
looked for. By this indefatigable observer, 
we are made acquainted with a new pri- 
mary planet belonging to our system, called 
the Georgium Sidus, attended by six satel- 
lites, which he discovered on the IStli of 
March, 1781, and which being at twice the 
distance of Saturn from the sun, has doubled 
the bounds formerly assigned to the solar 
system. We are also indebted to him for a 
variety of observations on several other in- 
teresting astronomical subjects ; such as the 
discovery of two additional satellites to Sa- 
turn, of which the number is now seven ; a 
new method of measuring the lunar moun- 
tains ; the rotation of the planets on their 
axis ; on the parallax of the fixed stars ; ca- 
talogues of double, triple stars, &c. ; of ne- 
bulae ; and of the proper motion of the sun 
and solar system ; the accounts of which, to- 
gether with many other valuable papers, he 
has communicated from time to time in dif- 
ferent parts of the Philosophical Transac- 
tions. A new planet has been discovered by 
M. Piazzi of Palermo, between Mars and 
Jupiter, to which has been given the name 
of Ceres Ferdinandia; another by Dr. 
Olbers; a third and a fourth have also been 
discovered, which we shall briefly notice 
farther on. 
OF THE APPARENT MOTIONS OF THE HEA- 
VENLY BODIES. 
Having given a very brief sketch of the 
history of this science, than which, few if 
any, have higher claims to our veneration 
and regard, we proceed to consider the sci- 
ence itself, intending to present the reader 
with a popular outline of the study, freed 
as much as possible from mathemetical prin- 
ciples, upon which it depends, but for which 
few, in comparison, can be supposed from 
previous studies to have any taste. 
When we cast our eyes towards the hea- 
vens, we perceive a vast concave hemi- 
sphere at an unknown distance, of which 
the eye seems to constitute the centre. The 
earth stretches at our feet like an immense 
plain, and appears to meet and to bound 
the heavenly hemisphere. The circle around 
where the earth and heavens seem to meet 
and touch each other, is called the horizon. 
It is natural to imagine, that besides the 
hemispere which we perceive, there is an- 
other, exactly similar, concealed from our 
view by the earth, and that the earth there- 
fore is suspended in the middle of this hea- 
venly sphere, with all its inhabitants. A 
little observation turns this suspicion into 
certainty ; for in a clear evening the hea- 
venly hemisphere is seen studded with stars, 
and its appearance is changing every in- 
stant. New stars are continually rising in 
the east, while others are setting in 
the west. Those stars, that early in the 
evening are seen just above the eastern ho- 
rizon, will at midnight be seen in the mid- 
dle of the starry hemisphere, and may be 
traced moving gradually towards the west, 
till at length they sink below the horizon. 
If we look to the north, we perceive that 
many stars in that quarter never set at all, 
but move round and round, describing a 
complete circle in 24 hours : these describe 
their circles round a fixed point in the hea- 
vens, and the circles diminish more and 
more the nearer the star is to that point. 
This fixed point is called the north pole. 
There must be a similar fixed point in the 
southern hemisphere, called the south pole. 
In this way the heavenly sphere appears to 
turn round two fixed points, called the 
poles, once in every 24 hours. The imagi- 
nary line which joins the points is called the 
axis of the world. We shall endeavour to 
illustrate this by means of a figure. 
Let HO (fig. 1. Plate If.) represent the 
circle of the horizon, seen edgeways, when 
it will appear as a straight line: let 
HPERQ represent the complete sphere 
of the heavens, of which H M O is supposed 
to be the visible hemisphere, and HNO 
the invisible hemisphere : then P will be the 
pole or fixed point among the stars, visible 
to us, round which they ail appear to turn, 
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