164 Dr Horner on the Specific Gravity of Sea^ Water ^ <^'c. 
however, does not go much deeper than from twenty-five to 
fifty fathoms ; and at an hundred fathoms it is already within the 
limits of the accuracy of such observations ; for we have, 
( 6th June, 9, ° 4 Reaumur. 
For 100 fathoms -< 13th September, 9, 4 — 
14th September, 8, 6 — 
3. A certain coincidence with these results, only on a greater 
scale, is shown by the experiments of the 15th of November 
1817, in 9° N. Lat,, and 205° W. Long., in which the tempera- 
ture decreases from the surface to about sixty or seventy fa- 
thoms, rapidly and uniformly, from 24°, 7 R. to 8°,8 R. From 
9 to 101 fathoms, this rapid dectease, instead of proceed- 
ing, is suddenly reduced to the small amount of 0°,9 R. 
But if we compare these observations with those immediately 
preceding and succeeding them, of the 13th, 14th, and 17th 
of November, we shall hesitate to draw from them decisive con- 
clusions. 
The observations of 13th April 1816, in 15° S., and 130° 
W., follow a quite different course from those in September 
1817, in 36° N. The decrease of warmth from the surface, 
to as far as a hundred fathoms’ depth, is much more inconsider- 
able, being here only 3°,6, there nearly treble, namely, 9'’4, 
Reaum. It becomes more considerable between a hundred and 
two hundred fathoms, ijamely, 8*, 8 R. Remarkable as this 
inequality is, it yet seems impossible to ascribe it to an error in 
the observation, such as too soon drawing up the thermometer ; 
for, on the one hand, the regular course of the experiments of 
the 14th September 1817, and their coincidence with those of 
the 13th, at the depths of 0, 25, and 100 fathoms, does not 
allow us to suppose any thing of the kind ; on the other side, 
the observations of 18th April 1816, find their confirmation in 
the preceding ones of the 7th April, in 18* S., which give a 
difference of 0 to 125 fathoms of 4°,8 R., that is, from 0 to 
100 fathoms ; likewise 3®, 8 R. The same observations then 
give for the second hundred of the depth in fathoms, likewise 
about 8^ Reaumur. 
It is not to be discovered from tlie observations, whence this 
difference in the progressive decrease of the warmth arises. 
Jt cannot well be ascribed to the influence of the seasons, at 
