12. On the Temperature and Saltness of 
shown by M. Ermaan that salt water having a specific gravity of 1.027, 
the mean of that of the sea, diminishes in bulk gradually down to — 
5° F., and does not reach its maximum density before congelation. — 
M. Ermann’s experiments on this contraction extended from 59°F. 
to 25°, M. Lenz extended them up to 86°, and thence deduced a — 
law for reducing the specific gravity at any one temperature to what — 
_ it would be at any other. The following table exhibits the specific — 
gravity corrected to the temperature of 63.5° F., distilled water “ 4 
that temperature being reckoned unity. 
S| Depth in] SPECIFIC GRAVITY. e 
No.| Lat. N. Lon. E. ' a og | At surface.] Beneath. Difference. 
¥ } 7920". 21959" 539,0 | 1,02574 | 1,02645 | —0, i] 
2.) 21 14 ).196. 3.2... 660,124 0220) 1,02666 +0,00035 | 
se se 66 
From this table we see ‘that in the experiments No. 1 and 4 the - 
specific gravity of sea water towards the bottom is a litde greater 
than at the surface, but that the contrary holds in Nos. 2, 3, and foe 
In experiaett 7 the specific gravity of the surface differs so little 
1 that of the bottom that we may consider them as equal, For 
the first two cases we may suppose that a rapid evaporation had at 
that time determined the slight increase of density at the surface, a5 
abundant rains may have diminished it in experiments 2, 3, and 5. 
It is remarkable that in the same place the specific gravities are al- 
most exactly the same for different depths, if we except that of the — 
surface. No. 6 alone offers a striking exception, giving at the depth — 
of a thousand fathoms a specific gravity much less than at the sur- — 
face. , We cannot suppose this difference to be due to an error of 
after. The irregularity may perhaps be due to a current of colder 
and less salt water fowing at the bottom from the pole to the equa-_ 
tor,—a point, however, which can be determined only by repeated 
| 929.4 1,02659 | +0,00042 
/3 25 6 | 156 58 | 167,0} 1,02706 | 1.02674 +-0,00032 
4 \ 41 12 | 141 58 | 205,0| 1,02562 | 1,02609 | —0,00047 
‘“ ee 512, ‘c ,02658 — 0,006 6 | 
5 |82 6 | 136 48 | 214,0/ 1,02678 | 1,02624 | +:0,00054 | 
«|e “ 50,2; | 1,02651 | +0,00027 
«| « « | §92,6' « {| 1,02629 | +0,00049 | 
6 | 32 20 | 42 30 1014,7/ 1,02825 | 1,02714 | +0,00111 | 
7 |45 53 [15.17 | 3964 1,02738| 1,02732 | +0,00006-| 
a 
3 
ation, the specific gravity at the bottom being the mean of 
ations agreeing with each other, and that of the surface 
onding with the observations of the day before and the day 
