1301.) 
has laid before the Clafs the objects ex- 
tracted by him from under the lava, and 
which eftablith the faéts here prefented, in 
an inconteftible manner. 
METEOROLOGY. 
Agreement between the Variations of the 
Atmofphere in a large extent of Country. 
_ We noticed in the laft Quarterly Sitting, 
the efforts that Citizen LamarcK has 
made to determine whether the variations 
of the atmotphere are marked by any 
thing periodical. He has fince been em- 
ployed on a no lefs important object, to 
know whether they extend to great dif. 
tances. In fact, he has plainly difcerned, 
that without this condition, all the means 
reforted to,to prediét them, could only ferve 
for a given place; and that a particular 
labour would be requifite for every dif- 
trist. ‘To proceed in order, he at firft 
attached himfelf to only one fpecies of 
variations—that of the gravity of the air 
marked by the barometer; the following 
» is the method which he employed to render 
_ his refults more ftriking. He traced on 
a paper twenty-fix parallel lines reprefent- 
ing the {pace in which the barometrical 
variations are commonly limited in our 
climates. Other lines, perpendicular to 
the former, reprefent the days, and by 
marking on each the heights obferved, he 
traces a curved line which reprefents the 
progrefs of the mercury. 
Having then traced fucha line, agree- 
ably to the obfervations which he has 
himfelf made at Paris ;\ a fecond, agree- 
ably to thofe of Citizen PicretT, Affoci- 
ate Member of the Infiitute at Geneva ; 
and a third, agreeably to thofe of Citizen 
Tuutts, another Affociate of the Infti- 
tute at Marfeilles, he found that thefe 
lines afcend and defcend generally toge- 
ther, and fearcely differ but in refpect to 
the height of the place of obfervation, or 
only. as to the extent of the variations, but 
not as to their dire&tion. , 
' He found in the Memoirs of the Aca- 
demy for 1708, a note of Maran, 
which indicates the fame concordance be- 
tween the heights of the barometer ob- 
ferved at Paris and at Zurich. ‘This 
valuable remark had neither been re- 
pealed nor confirmed by any one fince. 
. ON BELEMNITES. 
We give this name to foffils in form of 
a lengthened.cone, ofa weaver’s fhuttle, 
or fometimes of a fpindle, which appear to 
‘be kernels of unknown fhells; they are 
pretty abundant in certain orders of moun- 
tains, and efpecially in marble, and other 
¢alcareous ftones, which contain cornua, 
Proceedings of Learned Societies. 
331 
ammonis and other foffils, the living ana- 
logies of which have-not yet been difco- 
vered. : 
Citizen Sace, who had defcribed many 
new fpecies of them, in one of the laft 
numbers of the Fournal de Phyfique, has 
lately communicated fome tothe Clafs, 
which he had not feen before, and which 
form an interefting addition to this part of 
the progrefs of our knowledce. 
Programma of the Prizes propofed by the Nationat 
Infiitute of Science and Arts, at the Public 
Sitting, the 15th Vendemiaire, in the 10th 
Year. 
CLASS OF MATHEMATICS AND PHYSICS. 
Subje& of the Prize of Chemifiry. 
The Clafs of Mathematics and Phyfics had, 
in the year 8, propofed forthe fubjet of a prize’ 
which the Inftitute would determine on the 
15th Vendemiaire, inthe roth year, the fol- 
lowing: 
To point out the earthy fubfiances and the proper 
procefs for making a kind of pottery, capable of 
bearing a fudden tranjition from heat to cold, and 
which will be within the ability of perfons of alt 
claffes. 
At the endof this notice, the programma 
adds, 
“© The art of fabricating the more valuable 
pottery, known by the name of porcelain, has 
arifen to fuch perfection in the Republic, as 
to leave fcarcely any thing to be defired ; 
but the cafe is different with the fpecies of 
pottery which is in common ufes this kind of 
ware is very far from-that ftate of improve- 
ment and perfeétion fo neceflary to fupply the 
wants of the great body of citizens. Mean- 
time, fome of the neighbouring nations, wha 
cannot manufacture porcelain equal to ours, 
make a pottery much fuperior to that made in 
France. The Inftitute, therefore, require 
the candidates to examine the compofition of 
thefe potteries, to difcover the earths which 
have been ufed in their compofition, or point 
out fuch artificial mixtures as will fupply 
their places; the manner in which thefe 
earths “ould be treated to give them the ne- 
ceflz qualities; the art of baking; the de- 
gree of heat, and the form neceffary for the 
furnace; but, above ali, a method of glazing 
them without the oxydes of any injurious 
metal,” 
The Clafs has received only one Memoir 
on this fubje€t; accompanied by many fam- 
ples of pottery and of the earths of which they 
have been made. The Memoir is written 
with perfpicuity and method, contains the ac- 
knowledged principles of philofophy and che- 
miftry, and the details which are employed to 
explain them fhew a long and attentive prac- 
tice of the art of pottery, joined to much 
knowledze of the theory 3 but the patterrs 
which accompany the Memoir do not meet 
the ideas pointed out-by the Clafs. Confe- 
guently, the diftribution of the prize is pof- 
Uuz2 poned 
