322 Prof. Bache’s Lecture on the Gulf Stream. 
met the sudden rise to the Gulf Stream shown especially below 
50 fathoms and termed so appropriately by Lieut. George M. 
Bache the ‘cold wall,” that navigators have not hesitated to 
receive the term into use; next the hot water of the Gulf Stream, 
rising to a maximum of 82°, then falling to a minimum of 80° 
rising to a second maximum of 814°, falling to a second mini 
mum of 78° and rising from this toward a third maximum. 
With these results the curves at 5 and 10 fathoms and those at 
20, 80, 50, 70, 100 and 150 fathoms agree and, with characteris- 
tic differences, those of 200, 300, 400 and 500 iathoms. 
The cold wall at 20 fathoms shows a rise of 19° in 25 miles, 
three quarters of a degree to a mile, and at 200 fathoms of 16°, 
in the same distance; at the surface it is nearly 8° in 50 miles. 
The cold water between the Gulf Stream and the shore has two 
well marked maxima and two minima in it, of which one seems 
to correspond in position to the sudden deepening of the water 
100 miles from Sandy Hook, as shown by the Coast Survey off- 
shore chart between Gay Head and Cape Henlopen. 
_ These results are more distinctly seen by grouping the curves 
into natural groups and taking the mean of their indications. 
Diagram No. 5 Plate I, gives the group of six curves from the 
surface to 30 fathoms, of four curves from 40 to 100 fathoms, 
both inclusive of 200, 300, and the single curve at 400. 
Similar groups are shown on Diagram No. 6, Plate I, from 
Cape Henry, the cold wall, three maxima of temperature and 
three minima being very distinctly seen. The results of three 
different explorations of this section, by three different officers, 
in three different years, are shown upon the same diagram. T 
coincidence of result could hardly be better. ‘The average of the 
whole of the observations is shown in No. 6 bis, Plate I 
? 
ond class of diagrams 
The conclusions deduced from the examination of all the 
sections between Cape Florida and Sandy Hook is, that the Gulf 
Stream is divided into alternate bands of hot, or warm and ¢00 
or cold water, the most distinct of which is that containing the 
axis of the Gulf Stream. 
That between the stream and the coast there is a fall of tem- 
erature so sudden that it has been aptly called the cold wall, 
ess distinct at the surface and where the overflow from the Ff: 
Stream passes furthest toward the shore, but still distinctly 
marked even at the surface. 
