| 
) 
& 
Prof. Bache’s Lecture on the Gulf Stream. 319 
‘of the Survey. Charles H. Davis, George M. Bache, S. P. Lee, 
Richard Bache, John N. Maffitt, T. A. Craven, Otway H. Berry- 
nan, B. F. Sands and John Wilkinson make up the list of our 
successful observers in this field within the last sixteen years. 
Their names you will see attached to the sections run by them 
on the general chart of the Gulf Stream presented to you this 
evening. 
» . The tirst was run in 1844, from Nantucket south and eastward, 
by Commander C. H. Davis, now the accomplished Superinten- 
dent of the Nautical Almanac, and the last in 1860 by Lieut, 
John Wilkinson, from the Tortugas, southeast to the coast of 
Cuba. The work still goes on perseveringly. 
The number of sections run has been fourteen, the number of 
Positions on these sections occupied 300, and the number of ob- 
servations made for temperature 3600. The limits below which 
the stream and the adjacent waters have been explored for tem- 
and from the Tortugas to 94° E. of Cape Henlopen. ‘The dis- 
_ lance along the axis of the Gulf Stream to the most north- 
‘astern point in the North Atlantic, measures nearly 1400 nau- 
tical miles, 
III. Meruop or Discussion or tae Resvtts. 
These have generally been discussed by diagrams, sometimes 
by analytical formule ; the former method is generally best adapt- 
ed to the character and degree of accuracy and circumstances 
of the observation ; the diagrams finally adopted after trials were 
chiefly of three different kinds, one for the discussion of the 
change of temperature with depths, the two others for the change 
_ Of temperature with position as well as depth. Of the first of 
these diagrams Nos. i and 2, Plate I, arespecimens. The depths 
Constitute the ordinates and the temperatures the abscissz of a 
“urve, showing the law of change of temperature with the depth. 
Upon the horizontal lines at the top of the paper the tempera- 
tures from ten degrees to ten degrees Fahr. are written and on 
the vertical line at the side, the depths. The separate observa- 
_ Hons being represented by dots; the curve is drawn with a free 
the 
hand amon m. <A 
The next two classes of diagrams give the distribution of tem- 
Peratures across the sections. In the first the temperature cor- 
"sponding to the same depth; in the second the depths corres- 
comin to the same temperatures. In this latter the figure of the 
ttom is shown when ascertained. In both classes the distances 
from the cape, or headland, city or inlet, which is the origin of 
the section is marked, and the several positions occupied for ob- 
“ving, so that the abscissm of the curve are the distances from 
