1804.] | 
Caffini, the fon, gave a defcriptive ac- 
countof thefe obfervations in the Memoirs - 
- of the Academy for the Year 1710, as, 
’ 
 folicgitude of the clafs. 
likewife, of others more ancient, made at 
Brelt, in 1679; and at Bayonne, in 1680, 
by Lahire and Picard. He, likewife, gave 
a difcuffion, in the Memoirs of 1712 and 
1713, On a long feries of obfervations 
‘made at Breft, inthe years r711 and 1712. 
This feries was begun by M. Montier, 
thence continued and extended to the year 
4716, by M. Coubart, an able profeflor of 
navigation. Thefe latter obfervations 
were particularly valuable for the number 
and the exaét care with which they were 
drawn up. It is to be regretted that the 
obfervations of the year 1713 have been 
loft. 
Although Caffini was attached to the 
fyftem of Defcartes, which was then in 
vogue, it is no lefs true that his labour 
on the fubje&t of the obfervations we have 
jut f{poken of, is very ufeful, and, for a 
long time, formed the only pofitive docu- 
ments relative to the courfe of the tides. 
By the help of this labour, D. Bernoulli, 
aided, moreover, by theory, formed his 
Table of the Retardation of the Tides, which 
has been, and ftill is, fo ufeful to naviga- 
tors. Premature fyftems perith, but facts 
are eternal. 
We might here quote a, multitude of 
occafions wherein the Academy of Sciences 
has not only endeavoured to accelerate the 
rational progrefs of the fciences, but, like- 
wife, applied itfelf to the moft important 
objects of public utility. No learned fo- 
ciety has carried its folicitude fo far in 
thefe refpeéts ; and the marine, in parti- 
cular, is under eternal obligations to it. 
It is to the Academy of Sciences, that 
maritime Europe is indebted for the firft 
principles in the theory of the contruction 
of veflels, working of them, &c. as alfo 
the firft judicious notions reiative to the 
guaging of veffels, &c. 
Exclufive of theory, the calculation of 
the tides repofes upon faéts ; and _princi- 
pally on the knowledge of what we call 
LEtablifement des Ports; or, the Tables 
taken at the Ports. We have, indeed, 
pretty ample documents; but they re- 
quire to be reétified, and they call for the 
The ftate of the 
with a precifion adequate to our ‘other 
P= number of the ports is not known 
knowledge ; nor even with that which the 
fafety of navigation requires. A faét re- 
markable enough is, that the late expedi- 
Proceedings of learned Societies. 
508 
tions round the world have furniihed us, 
in regions many thoufands of leagues dif- 
tant from us, with more correét data than 
thofe we are in pofleffion of, for many of 
our neighbouring ports, which we frequent 
“every day. 
The feries of the obfervations at Breft, 
fpoken of above, forms an aggregate, the 
theory of which furnifhes all the refults 
with a wonderful precifion. Similar ma- 
terials for the other ports would, doubt- 
Jefs, leave nothing further to be withed 
for, as to the practical part, but fill it 
_would be always ufeful to make obferva- 
tions, and elfpecially in circumftances 
wherein a number of cafes concur together 
to form greater or leffer tides. It would 
be therefore of importance to make ob- 
fervations when the perigee or the apogee 
of the moon and of the fun concur with 
the /yzygie; when the perigee of the moon, 
concurring with the /yzygie, thefe two 
ftars are near to the equator or to the tra- 
pics, &c. The tides of the quadratures, 
although of lefs importance for the opera- 
tions of the fea-fervice, are yet not the lefs 
interefting in their courfes; and, in all 
cafes, obiervations become important, in 
order to afcertain the effect of acceflary 
circumftances. We conftantly obferve 
eclipfes, although it be no ways neceffary 
to verify the principles upon which their 
prediction is eftablifhed. 
The tide of the new moon of Germinal 
laft, furnifhes an example of the utility of 
obfervations; it was obferved at Breft, 
by our colleague Rochon. The circum- 
ftances were highly favourable to produce 
a very high tide, and this in effe&t took 
place. But what renders this obfervation 
truly important is, that the weather being 
almoft calm, this tide was folely produced 
by the general caufe without any compli- 
cation of meteorological circumétances ; 
and was no lefs, on that account, one of 
the higheft that has been ever obferved in 
that port. The obfervations of the fame 
tide, made at Calais, by M. Septfontaines, 
are likewife very important. 
Agreeably to the above confiderations, 
the clais wnofe principal objeé& it is to 
extend its refearches to all objeéts of pub- 
lic utility, cannot but take a egreat inte 
reft in the plan of oblervations tnat we are 
about to propofe to it; and which may 
ferve for inftreétions to the perions that 
fhall be appointed to carry it into execu 
tion. This example will not fai! to be 
followed up by forcign nations. In this 
4D 2 laft 
