330 
pulous accuracy which the author would! 
beftow on every part, the bad ftate of his 
health, the dificult circumftances under 
which he had begun the impreffion, the re- 
folution he took to cancel and to begin 
again a confiderable part of the edition, 
which he had not been able to fuperintend 
properly himfelf, and in which he had 
found fome faults of little importance in 
refpeét of truth, but yet pretty numerous; 
thefe caufes deprived him of the fatisfac- 
tion of compleating a work he had very 
much at heart, and for which hehad made 
great facrifices. The preface found in his 
papers was incompleat. The part which 
remained to be done would, doubtlefs, have 
been the neweft and the moft interefting. 
What he has left of it contains fcarcely 
any thing but a fyilabus of the theory of 
logarithms, after Euler, and the ufages of 
his tables. We find in them, however, 
a new and very expeditious formula to 
calculate the logarithms of numbers. He 
had {aid nothing of the conftruction of his 
tables of fines. The editor has endea- 
voured to fupply what was wanting in this 
introduétion ; he has given new formulz, 
and both: fure and expeditious procefies 
to conftruét, verify, or extend all the 
tables which contpofe this collelion. He 
has compared thefe tables with all thofe 
of the fame kind which he could procure, 
in print or manufcript, and has {pared 
neither labour- nor care to infure the cor- 
re€tion of this work, the typographical 
execution of which does honour to the 
printing-office of the Republic. 
Citizen LALANDE has read a Memoir 
en the longitude of Florence, the pofition 
of which was remarkably uncertain. 
From the new obfervations he has’ re- 
ceived from Chevalier CrccoLini, and 
which he has recently calculated, he finds 
the difference of the metidians of Paris and 
Florence, to be 35' 40”, 
Citizen Lalande has read another Me- 
moir on the fecular motion of Venus. He 
has difcovered by the laft inferior con- 
‘junction of this planet, that the epoch of 
the longitude is exaét, as well as the equa- 
tion of the orbit, and that there remains 
nothing to be changed, in this refpect, in 
the laft Tables. In thefe ealculations, Cit. 
Lalande has kept an account of the per- 
turbations that Venus experiences from 
the action of Jupiter and from tha of the 
earth, accordiyg to the formule which he 
himfelf gave in the Memoirs of the Aca- 
demy of Sciences. 
NEW GALVANIC EXPERIMENTS,» 
Citizens FouxcrRox, VauQuaLin and 
Proceedings of Learned Societies. 
[Nov. £ 
THENARD, who are occupied in the ma< 
nagement of thefe experiments, have been: 
lately recompenfed for their labours by 
the difcovery of one of the moft curious and 
the molt important faéts which have a re~ 
lation to this order of phenomena. 
It was already known that by multiply 
ing the difcs which compofe the pile, the 
force of the commotions and the rapidity 
of the decompofition of the water was aug- 
mented ; they wifhed, however, to {ee 
what would be the refult if the furface of 
each difc were augmented; they, confe- 
quently, compofed a pile with plates of a 
foot {quare. ‘The commotions and the de- 
compofition remained the fame as witha 
‘fimilar number of fmall difes; but the 
combuftion of the metallic wires operated 
on the fpot, with much foree, and, by 
plunging them into oxygeme gas, they 
were feen to flame with a very lively éclaty 
while fmall plates, however great the num- 
ber of them may be, produce no fuch ef 
fe&. Thus combuftion follows a law re~ 
lative to the furface of the plates, while 
the other phenomena have reference only 
to their number. 
GEOLOGY. 
Oz the Eruption of Vefuvius, iu theYear 2,5 
One of the moft important points to de- 
termine in the hiftory of Volcanoes is, the 
degree of heat neceflary to give fluidity 
to lavas: **Is it a fire of fufion -fimilar 
to that which produces glafs ; or is this 
fluidity owing to fome other caufe?” 
This queftion has long occupied the atten- 
tion of Citizen DoLomiev, who had al- 
ready entertained fome doubts (on confi-: 
dering many of the fubftances contained in 
the lava, and which remained untouched 
in it, although very fufible in themfelves} | 
with refpect to the great heat which is 
commonly attributed to thefe volcanic 
mines. The eruption of Vefuvius, inthe 
year 2, furnifhed him with the means of 
afcertaining this degree of heat, fo te 
{peak, as with a thermometer; he made 
it his bufinefs to trace the effeéts of the 
Javas on the fubftances which it had in- 
veloped, and principally on metals. 
He found, after this examination, that 
volcanic heat does. not furpafs that which 
is capable of melting filver, and that it is ” 
lefs than would be requifite for melting 
copper, The metals fufceptible of being 
oxydated in a heat Jefs than what would be 
neceflary to melt them, have been fo,even in _ 
the centre of the moft voluminous mafles 5 
lead has been converted into a teflulary 
galena with large faces, glafs into porce- 
Jain of Reaumar, &c, Citizen HVA } 
- has 
