at great depths, far from Land. 297 
-ed but to 2° below the temperature of the surface, whilst the same 
thermometer, placed, as I have stated, in the place of the one bro- 
ken by pressure, fell 11°: incontestible proof, in every respect, of 
the superiority of our apparatus, and of the defectiveness of the 
double valved cylinder. : 
Third experiment of one thousand two hundred feet, by 5° north 
latitude. 
The experiments above related have been made at inconsiderable 
depths, and with a less perfect apparatus than the one of which I 
have given a description ; it remains to describe two other observa- 
tions of the same kind, more recent also, having been made during 
our return voyage from India to Europe, with an instrument better 
constructed, and at depths much greater. The 19th of February 
1804, we found ourselves within the tropic, becalmed so that our 
vessel remained motionless on the surface of the water; to avail my- 
self of such favorable circumstances, I desired the commanding offi- 
Cer to permit me to try some new experiments. I had previously 
Constructed my apparatus nearly in the manner I had conceived prop- 
er. I sunk it to one thousand two hundred feet; it remained there 
one hour and fifty minutes, not including the time of drawing it up, 
Which was seventeen minutes. It was at twenty seven minutes after 
five ; the atmosphere indicated +25° 7 of Reaumur; the surface of 
the water was at +24° 5/. My th ter drawn from the depth of 
one thousand two hundred feet, marked no more than +7° 5, cold- 
hess already very considerable, doubtless, and which had been much 
§reater, had it not been for the difficulties of which I have spoken in 
the first experiment, the most part of which occurred in this. Nev- 
ertheless, the results of this kind of experiment, always analagous to 
the preceding ones become the more interesting, as they prove still 
further the progressive lowering of the temperature in descending to 
the bottom of the ocean. The following observation would have 
dissipated all my doubts, had any remained. 
Fourth experiment of two thousand one hundred and forty four 
feet depth, by 4° north latitude. 
The 22d of February, I took advantage of the continuance of the 
calm to repeatmy interesting trials; two thousand one hundred and forty 
four feet of cord, were sent to the bottom of the sea at fifteen minutes af- 
ter eleven in the morning, we d drawing it up at thirty - 
ter noon; it took forty five minutes through the ill will of the crew, 
‘0 whom observations of that kind afford little pleasure. The entire 
Vou. XVH.—No. 2. il 
