56 
Citizen Lacrorx has communicated his 
views refpeSting the, neceffity and the 
means of making new experiments on the 
refiftance of fluids. é 
Citizen Duc La CHaPeL_Le, an Affo- 
ciate Member, has fent us a very circum- 
fantial Memoir on the winter of the-year 
8, whicly deftroyed half of the harvett in 
the South of France. He finds the prin- 
cipal caufes of this calamity in the want 
of fnow, the falfe thaws, and the very 
abundant white frofs. 
In {pite of the almef continual rains, 
we have been able to obferve, in the entire 
circle, the folititial declination of the fun. 
Thefe obfervatiens, although few in num- 
ber, have confirmed the fingular refult, 
which has made us already find many 
times the obliquity of the ecliptic lefs, 
by fome feconds, in winter than in fum- 
mer. This fmgularity appears to accord 
with the yet imperfed&t kuowledge, both of 
abfolute refraction, and of the variations 
which it experiences in the different ftates 
of the atmofphere. 
Citizen LeGeEnDRE has given a third. 
edition of his Geometry, and Citizen 
Lacroix, the fecond of his Elements of 
Algebra. The rapidity with which thefe 
re-impreflions fucceed each other, at the 
fame time that it proves the merit of thefe 
works, thews likewife how far the ftudy 
of the mathematics is fpreading in France. 
The Executive Commiffion of Piedmont, 
to whom Citizen VassaLa has carried the 
models.of the metre and of the kilogram, 
writes to the Inititute, that they are about 
to nominate Commiflaries, authorized to 
eftablifh, with the greateft precifion, the 
relations of the meafures and weights of 
Piedmont, with the new meafures of 
France. They announce, alfo, that they 
will contribute, with all their power, to 
make known the advantages of the new 
fyftem, the effet of which will be to ap- 
proximate the relations which ought to 
unite more nearly the two nations. 
Two numbers of the Eevptian Decade 
have procured us fome notices of the la- 
bours of the Inftitute of Cairo; we dif- 
tinguifh in it—1. A Memoir of Citizens 
EANCRET and CHABROL, on the means 
of re-eftablifhing the Canal of Alexandria, 
the reftoration of which would be no lefs. 
ufeful to agriculture than to commerce.— 
2. A Table of the Latitude and Longitude 
of different points of Uppér and Lower 
Egypt, by Citizen Nowe, and the ob- 
fervations of the fame aftronomer to de- 
termine the courfe of the Nile from Syene 
to Cairo; a new and important labour, 
executed in the mof exact manney.—3. 
Proceedings of Learned Societies, 
[Aug. 4, 
A Memoir on the Mekyas of the Ifle of 
Raoudah, by Citizen LEPERE. This 
monument, conftructed by the Caliph Al- 
mamon, in the year 211 of the Hegira, is 
a well, which communicates, by a fub- 
terraneous canal, with the Nile, and whofe 
waters are, confequently, always on a 
level with thofe of the river. In the mid- 
dle of the well rifes a column of marble, 
divided into cubits, palms, and digits, 
which indicates the rife of the water. 
The obfervation is made commodioully, 
by means of a ftair-cafe, which winds 
about the interior, -n»xt to the inner 
wall of the well. At the arrival of the 
French, this well was almoft filled up by 
the depefits of the Nile, fo that it only 
communicated with_the river by filtration. 
Citizen Lepere has thoroughly cleanfed it ; 
the column has been pai laid hare, and 
the divifions have been found more equal 
than had been commonly reported. The 
medium fize of each of the 16 cubits is o® 
54’.—The preceding details on the Mekyas 
or Nilometer have been given by Citizen 
Monge. To perpetuate the utility of prior 
obfervations by the Mekyas, in cafe this 
monument fhould happen to be deftroyed, 
Citizen Lepere prefents to pofterity an in-. 
variable rule to appreciate the ulterior ex- 
hauftments of the Nile, and of the level of 
the valley. This point is taken on the 
focle or foundation at the north angle of 
the calcareous layer or ftratum, which 
ferves fora bafe to the great pyramid, and. 
it is more elevated by 42°. 5/.- than. 
the chapiter of the column of the Me- 
kyas.— 
4. Andlaftly, an extenfive Memoir on the 
agriculture and commerce of Upper Egypt, 
by Citizen GiRAxD, ‘who terminates it 
thus :—‘* What fuccefs ought we not to 
hope for from the labours undertaken for 
the amelioration of Egypt, which, placed 
in the centre of the antient Continent, may 
colleét ali its produétions in one, as it is, 
by its pofition, the moft natural entrepét of 
the commerce of the world 2” . 
In the phyfical part, the -allowed time 
has only permitted an arid nomencla- 
ture of the important labours of the Clafs; 
but, in Chymifiry, Citizen BERTHOLLET 
has proved, that the propagation of chy- 
_mical action is moderated—r1. by the 
weaknefs of that action, and—z by the 
changes. of conftitution to which the fub- 
ftances that exercife it are fubject. He 
has eftablifbed the limits of the chymical 
knowledge which has been hitherto ac- 
quired invegetable phyfiology—And laftly, 
he has fhewn that motion accelerates the 
communication of heat, by the near ap. 
proach 
