1809.] 
researches of M, Piazzi, and by those of 
M. Zach.—Your Majesty has deigned to 
accept of the dedication of these Tables, 
which the Board of Longitude has pub- 
lished with the Lunar Tables-of M. Burg. 
These likewise required a prodigious 
number of observations, of longer and 
nicer calculations, which would have 
been even impossible, had not the astro- 
nomer been assisted by the analysis of 
M. Laplace. The researches of MM. 
Masou and Burg determined the. periodi- 
cal inequalities. MIM. Burg and Bou- 
vard fixed the epoch of the longitude : 
but inequalities, difficult to unravel; 
equations, for long periods, which are 
Ganionaded during a long time with 
the mean motions, presented so many 
“insuperable difficulties, had not the ana- 
’ 
‘others 
. Setar n, 
lysis of M. Laplace once more furnished 
aclew, by means of which they found | 
their way out of this labyrinth. The 
same analysis determined equations, 
which were received with hesitation, and 
which had not been thought 
of. It secures to the new Tables of M. 
Burg an accuracy, at the same time, 
greater, more lasting, and more worthy, 
of the prize which has been adjudged to 
him, under circumstances. that perhaps 
never before occurred in the annals of the 
seiences—when the Institute had for its 
chief the powerful gemius who took plea- 
sure amongst us in crowning the arts of 
peace, and soon after crossed the Alps, 
again astonishing the world by his rapid 
marches, those ‘bold conceptions, those 
estan combinations, which made the 
art of war @ new science, the progress of 
waich it belongs not to us to describe. 
The perturbations of Mercury,’ of Ve- 
nus, and of Mars, no longer present dif- 
ficulties. Lalande, by a laboar of forty 
years, brought the theory of Mercury 
to a high Wegree of perfection. Four 
astronomers were simultaneously occu- 
pied with Mars; MM. Oriani, Lalande 
thie nephew, Triesnecker, and Monteiro, 
Jupiter and Saturn offered difficulties, 
which, for many ages to come, would 
perplex astronomers, Persuaded of the 
Ampossibility of properly representing all 
tle observations, Lalande confined him- 
self to the last.. Lambert gave empiri- 
cal equations, which might palliate the 
evil for some years. M. Laplace dis- 
covered the remedy in an equation, the 
period of which is upwards of nine hua- 
-dred-years, and which, during three hun- 
dred years appeared to accelerate the 
motion of Jupiter, and to retard that of 
To place this beautiful theory 
Progress of the Sciences. 
205 
in all its lustre, Delambre calculated, 
with the greatest care, all the.good ob- 
servations which were made since the re-" 
vival of astronomy, and reduced, almost 
to nothing the errors of the tables: but, 
of the observations which he was obliged 
to employ, those in which he could place 
entire confidence, formed the smallest 
number, Since accurate observations 
are multipli¢d, _M. Bouvard, by conti- 
nuing this work, and availing himself of 
the improvements added by M. Laplace 
to his theory, has succeeded in render= 
ing the errors really insensible. Uranus 
was discovered in 1781, by-M. Herschel : 
after eight years observations, a hope 
was entertained of knowing better its 
elliptic orbit, and its perturbations. De- 
lambre, by a happy application of the 
theory of M, Laplace, and a choice of 
excellent observations, succeeded so far, 
. that seventeen years, since expired, have. 
, Not indicated any sensible correction, 
M. Oriani, who, at the same time, was 
occupied with the same object, obtained 
the same success with respect to the per= 
turbations; and that he has not succeed-. 
ed equally in the elliptical part, can be 
ascribed only to the smailer number of 
observations of which he made use. 
M. Laplace determined the reciprocal . 
perturbations of all the principal planets, 
He had a similar work to perform for the 
satellites of Jupiter, M, Lagrange, in a 
work which manifested a very masterly 
hand, had already treated this subject in 
a manner totally new, by considering, 
at the same “time, the reciprocal attrac- 
tions of the Sun, of Jupiter, and of his 
satellites; he, in fact, resolved the pro- 
biem of the six bodies, but the subject 
was too rich to be exhausted by a first 
attempt.. M. Laplace, om resuming the 
theory, made inportant discoveries in it, 
by which it was completed ; however, it 
still contained several ar bitrary, constant 
terms, which could be determined only by. 
the discussion of a prodigious number ot 
observations, M. Delambre undertook 
this work, and the Tables, which were 
the result, are adopted ‘by all astrono- 
mers; notwithstanding “which, he has 
recommenced them on a more extensive © 
plan, and according to the whole of the 
observations made since the discovery of 
the satellites. This new work, whic h 
was finished two years ago, is now in the 
press, and will shortly be published, with 
the Tables of Saturn and Japiter By M, 
‘Bouvard. 
The problem of the, comets bas, been 
long considered as the most dite: ein 
ASPORONY.s 
