Retrospect of Domestic Literature.— Astronomy. 678 
Doctor,. “either provided with a case of 
instruments, or with a scale, and plane 
compasses only, is requested to learn the 
definitions out of book, and to construct 
all the problems throughout from scales 
of different extent; and always, from 
step to step, agreeably to the directions 
given under each problem, By such 
easy and amusing exercise -he_ will 
become capable of reading Euclid, 
‘or of entering upon the study of forti- 
fication, navigation, astronomy, &c. 
without the least perplexity ; and should 
he even limit his pursuit to the pages of 
this little work, the compiler hopes that 
the pupil will have acquired such habits 
of correctness and ingenuity, as-will be 
of continual use to him in any depart- 
ment of life.” 
“ The System of the World,” by P.S. 
Laptacr, Member of the National Insti- 
tute of France. Translated from the 
French by J. Ponp, F. R. S. 
The name of Laplace’ has long been 
celebrated among men ,of science. No 
man has written more profoundly on the 
subjects of astronomy, or obtained. a 
more solid reputation as .a mathemati- 
cian, as one who knows well how to apply 
the most abstract principles of science 
to practical utility. In the work before 
us we have the resulc of his deep specu- 
jJations in a popular form, adapted in ge- 
eral to the comprehension of all persons 
who have been accustomed to think and 
reason on thismostsublime ofthe sciences. 
After carefuliy examining the work, we 
scruple not to recommend it to the atten- 
tion of our readers: some parts of the 
fourth book may be considered rather 
abtruse, but the subject is simplified as 
much as possible; and those who take 
pains to understand it will admit that the 
time and Jabours expended on it, have 
not been thrown away. The first vo- 
lume treats “ of ‘the apparent and real 
Motious of the Celestial Bodies,” and 
** of the Laws of Motion.” The second 
explains ‘* the Theory of Gravitation,” 
and concludes with an ** Abridged His- 
tory of Astronomy.” Our readers will 
be glad to see a short extract or two, by 
which the style and manner of Laplace, 
and the fidelity of his translator, will be 
fairly exhibited.. In ascertaiming the dis- 
tauce and magnitude of Jupiter it is ob- 
served : 
“ Direct observation, or the known 
motion of the sun, gives the position of 
the earth as seen from its centre. Thus, 
imagining a triangle formed by the right 
{ines which join the centres of the sun, 
the earth, and Jupiter, we have in this 
triangle the angle of the sun, observa- 
tion will give that of the earth, and we 
shall get at the instant of the middle of 
the eclipse the rectilinear distance froin 
Jupiter to the earth and to the sun, ia 
parts of the distance from the sun to the 
earth. Nah 
** It is found by these means that Jue 
piter is ac least five times farther from us 
than the sun, when itsapparent diameter 
is 120’.* The diameter of the earth at 
the same distance would not subtend 
an angle of 11; the volume of Ju- 
piter is therefore at least a thousand 
times greater than that of the earth. 
“ The apparent diameters of these 
satellites being insensible, their magni« 
tudes cannot be exactly measured. The 
attempt has been made to appreciate it 
by the time they take to penetrate the 
shadow of the planet; but there is a 
great discordance in the observations 
which have been made to ascertain this 
circumstance. This arises from tlie vee 
rious powers of telescopes, the different 
degrees of perfection in the sight of the 
observer, the state of the atmosphere, 
the altitude of the satellites above the hee 
-rizon, their apparent distance from-Ju- 
piter, and the change of the hemisphere 
presented to us. The comparative 
brightness of the satellites is dependent 
of the four first causes, which only alter 
their proportional light, and ought there 
fore to afford information concerning the 
rotatory motion of these bodies. Dr, 
Herschel, who is occupied in this delicate 
investigation, has observed that they sur- 
pass each other alternately in brilhance, 
a circumstance that enables us to judge 
of their respective hyht. The relation of 
the’ maximum and minimum of their 
light with their mutual positions, has pé“- 
suaded hiin that they revolve upon them- 
selves like a moon in the period equal to 
the duration of their revolution round 
Jupiter.” is . 
Laplace has given the name Uranus 
to the planet discovered by Dr. Herschel, 
and which hitherto has generally been 
denominated after the discoverer, “ The 
Herschel:” we cannot approve of the 
change, and we wish the trantlator had 
resisted the innovation: we shall give 
the author's account of this planet: 
‘© Of Uranus and his Satellites.—The 
five planets that we have hitherto consi-__ 
dered have, been known from the most 
