Dr Horner on the Specific Gravity of Sea-Water ^ <^c. 165 
least in Lat. 35® N. : the observations of June and September, 
show an agreement with each other. The reason perhaps is, 
that the perpendicular rays of the sun penetrate the water, be- 
tween the tropics, to a greater depth than in latitudes where the 
sun never appears in the zenith. The place of constant tem- 
perature, independent of the seasons, must probably lie much 
deeper between the tropics than beyond them. 
5. The observations of the SSd of September 1817, in 28° N. 
Lat. and in 152° W. Long, seem to present a much more uni- 
form course, particularly if we set aside the statement in twenty- 
five fathoms’ depth, which does not appear to agree with the 
higher or lower observations. We have from them a decrease 
of heat, of 3°.5 R. for the first fifty fathoms ; 3°0. R. for the 
second fifty fathoms, and 4°.3 R. from a hundred to two hun- 
dred. 
The collective observations on the progress of the decrease of 
heat were made in the South Sea. From the Atlantic Ocean we 
received only a few insulated statements, for depths of a hundred 
to two hundred fathoms. The experiments in both oceans are 
arranged in the following Table. 
WARMTH qf the SEA-WATER at d^erent depths^ ar- 
ranged according to the Geographical Latitudes in degrees qf 
Reaumur"' s Thermometer. 
Month. 
<u 
«« 
O w 
05 1 
° J 
gi 
2 •S 
200 
thorns. 
300 
thorns. 
<u 
O 
d 
'O 
13 
U 
b 
CS 
CS 
O 
hJ 
April 
21.0 

17.2 
9.9 
1 
18 S. 
125 W. 
— 
21.4 
— 
17.8 
10.8 
— 
15 
134 
May 
22.6 
— 
13.5 


1 N. 
177 
Nov. 
24.5 
— 
10.7 

— 
9 
204 
In the South Sea. 
— 
23.0 
14.1 
— 

— 
12 
210 
Dec. 
22.1 
12.8 
— 

— 
16 
240 
— 
21.7 
16.6 
— 
— 
— 
18 
224 
Sept. 
20.1 
— 
13.0 
8.8 
— 
28 
152 
June 
18.7 
— 
13.5 
— 
9.4 
29 
199 
Sept. 
18.0 
9.3 
7.0 
5.4 
^6 
147 
(4.8)* 
* In 400 Fathoms. 
June 
13.0 
9-3 
— 
5.0 
37 
199 
Jan. 
io.4 
— 
— 
3.2 
— 
44 S. 
57 
March 
17.3 
— 
12.3 
— 
— 
34 
27 
f In the Atlantic. 
\ Ocean. 
April 
15.8 
12.8 
— 
7.9 

3i 
15 
Oct. 
18.9 
— 
10.6 
— 
_ 
30 N. 
15 
*“ 
1 16.4 
— 
~ 
11.0 
39 
1 
13 
