On the Distribution of Temperature in the Gulf Stream. 36 
It is altogether probable that all the depths found by observa- 
tion are greater than the actual ones; but the bottom was brought 
up in several cases showing that the lead had reached it, and it 
is most probable that the proportions are not far from correct. 
The close conformity of the curves of temperature to those of 
the bottom is obvious from an inspection of the diagram. The 
descent of the curve of 57° in the deepest part of the section is 
a remarkable feature, not obliterated in the curves above it, but 
reaching uearly to the surface. In the midst of general coinci- 
dences there is no one discrepancy which indicates that there 
may be other causes which produce the distribution of tempera- 
ture in warm and cold bands besides the figure of the bottom. 
Further observations will show if this is so, or if it is an error of 
observation. . 
n this diagram the cold water pressing towards the 
shore-side, following the form of the bottom along which it lies, 
and forcing the layers above it, to take the same general confor- 
mation. 
_ On the crest of the steep slope in the St. Simon’s section there 
1s a forcing up of the cold water to a considerable height, as Is 
shown less distinctly at position No. 1 of the Charleston diagram. 
This corresponds to the “cold wall” in those sections, 
hether this remarkable discovery may be the clue to the gen- 
eral distribution of temperature in the Gulf Stream, on the deeper 
Sections north of these, is well worth examining, and instructions 
ave been given accordingly. 
4. The “Cold Wall.” 
It is difficult to fix the depth of the Gulf Stream current, though 
easy to see, from the observations, that it is comparatively super- 
ficial, extending certainly, on the Charleston section for example, 
to a less depth than three hundred to five hundred fathoms, and 
resting upon cold water belonging to a much higher latitude than 
that in which it is found. Off Cape Florida, about twelve nanuti- 
cal miles east from the light-honse, at the depth of 550 fathoms, 
the temperature was but 49° Fahrenheit in June, 1853. The 
mean temperature of the coldest month in the year, on the coast 
in the same latitude with the point of the axis of the Gulf Stream 
at the surface on the Charleton section, is about 533° Fahrenheit. 
At Key West the mean temperature of the coldest month of rong 
Year is, from tbe report of the Surgeon General U. S. Army, 69:39. 
P-sea temperatures of the ocean generally, are required for 
determining this and other questions of a similar kind. 
: The lateral limits of the stream are more easily defined, espe- 
cially in the northern sections, where the change is so sudden 
m the warm water of the Gulf to the cold stream inside of it 
towards the shore, that the cold stream was likened, by Lieut. 
Geo. M. Bache, to a “cold wall” confining the warm water.  ~ 
