328 
my hands, and I perceive already by the 
regularity of its going, that the French 
Horlogerie will be able to furnifh the ma- 
rine with this new help for obferving the 
longitude in long voyages, as I remarked 
on occafion of that which Lovis BEr- 
THOUN gave to BEAUCHAMP.. 
On Oétober 17th government iffued an 
order for printing my Aftronomical Bib- 
liography, in one volume of 600 pages in 
4to.; a work which aftronomy wanted, 
and which will contain the ground- work 
of the hiftory of that fcience. 
We have received this year from Bou- 
loene the experiments which M. Gu-- 
LIELMINE has made at the tower of 
Adinelli, which is 247 feet in height; he 
has found that bodies fell eight lines and 
a half to the eaft of the plumb- line: the 
theory gives five lines; thefe experiments 
are very difficult to make; they prove 
however the motion of the earth, which 
Yortunately ftands-in no need of demon- 
firation. In England Dr. MASKELINE 
has publithed his ‘obfervations for 1795 ; 
and in the Philofophical Traniactions for 
3797, Dr. HERSCHEL has -given the 
period of the variations of light of two 
‘ftars, one of the crown (/a couronne) and 
one of the crown-piece (Pecu) of Sobiefki ; 
-the firft 10% months and the fecond §3 
days. 
Thus we have already ten changing 
flars, the periods of which we are ac- 
ee tee with, that is to > fay, the dura- 
‘tion of their rotations. ‘Ehere are many 
others Lise variations have been ob- 
ferved, but the periods of which we can- 
not yetaffign, -We have no knowledge 
of any other curious obfervations of Dr. 
HERSCHEL fince that of the rotation of 
Saturn, and of the exiftence of his two 
§nterior fatellites in 1790. He has pub- 
lifhed ihe det {cription of his forty foot 
telelcope; but it appears to me, that he 
isnot as yet fo well fatisfied with it as to 
allow afironomers to make obfervations 
with it, to whom, however, the indulgence 
- would be a great curiofity. 
Inthe ‘“ Bibliotheque Britannique,’ an 
: excellent journal publifhing at Geneva, 
we read a curious hiftory of Chennai 
obler vatory, the bu ilding of which was 
partly owing: fo a certain Frenchman, 
‘named St. Pieré, who pretended to have 
iound the longitude Yiu Str Nie a 
En Germany, M. Oupers has pub- 
ied a “Treatife on Comets, in which 
M. Vow Zacu has put fome which were 
not know, fo that he extends the number 
- of the o: bits hitherto ee eee 
that of this year, to 99. A large Treq- 
f 
Fiiftory of Afttoniony for VIG. 4. 
/ y 
[Nov. 
tifeon Aftronomy, publifhed in Englith 
by Mr. Vince, and one in Swedith by 
M. MELANDERHIELM, are intimations 
that a curiofity for aftronomy is growing 
more general in countries where hitherto 
the French publications were reckoned 
fufficient. 
M. VenTuR?, profeflor of natural phi- 
lofophy at Modena, who has pafled about 
a year with us, has made a feargh among 
the. manufcripts of Leonardo da Vinci, 
which I had demanded of our commiffaries 
in Italy, in order to verify the difcovery of 
the cauie of afh-coloured light (Ja lumicre 
cendrée) ; he has found the paflage, and 
he has configned it, with many other in- 
terefting articles, to an efflay which he 
has publithed at Paris, on the life and 
writings of that famous painter, whofe 
genius extended to a multitude of objeéts 
unknown in his time. Leonard was born 
in 1452, and died in 1519. 
The new Cifalpine Republic have 
eftablifhed an Inftitute at Bologna, or 
rather regenerated that which already 
fubfifted there, where there is alfo a re- 
{fpegtable obfervatory. 
In the ‘* Azxals of Chemifiry,” (vol. 
xxill. p, 175) we find an extract from the 
Memoir of .Dr. Buair, inferted in the 
fir volume of the Edinburgh Tranfac- 
tions, on aplanatic glafles, or thofe with- 
out aberrations ; he was authorifed in 
conferring a name ona difcovery which 
we owe to him. We find here, that the 
Doétor had conftruted an objeclive, con- 
taining mercurial cerrofive muriate, dif- 
folved 3 in alkohol, or in water, by adding 
to it a little muriate of ammoniac, and 
without any difpeifion of colours. 
The muriate of antimony diffolved j in 
alkohol or ether, with the addition of a 
little muriatic acid, to prevent the pre- 
cipitation, pofiefles the fame property. 
The great advantage of thefe compotitions 
iS, that there is no neceflity to recur ta 
fiint glafs, which it is difficult to procure 
of the proper clearnefs. 
M. Von ZacuH has juft completed a 
large work in two volumes, 8vo. which 
will conta in a valuable catalogue of 1290 
flars; determined with precifion to a fe- 
cond, as to the right afcenfions. J] haye 
furnifhed him with 2400 declinations, 
determined at the mural of tbe Ecele Mili- 
taire, the only obfervatory where the 
heights are numerous and exa&t enough to 
accompany the great and beautiful work 
of M. Vou ZACH. 
M. BopeE has publithed at Berlin, the 
four firft theets of a beautiful colleétion 
of aftronomical charts, 28 inches by 203 
they 
