128 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
In Prof. Libbey’s report for 1889 the vertical water temperature curves 
are represented by nine profiles, and twenty-seven sectional diagrams 
have been prepared for the report of 1890, as well as several plates show- 
ing the surface isotherms from time to time. The hourly changes of air 
and surface water temperatures for each day while the survey was in 
progress are also illustrated in the same graphic manner, being based 
upon the records made at the three stations and on board the vessels. 
Prof. Libbey has likewise summarized the resuits of observations upon 
the direction and force of the winds, as given on the Hydrographic 
Office pilot charts of the North Atlantic Ocean, in order to afford an 
insight, if possible, into the relations between the winds and the posi- 
tions taken by the northern boundary of the warm waters coming from 
the Gulf Stream. 
By means of the observations so far made it has been possible to 
indicate very clearly, for the region and periods covered by the exami- 
pation, the distribution of the bands of equal water temperature both 
vertically and superficially, and the relations of the cold and warm 
“water bodies to one another. The charts of surface isotherms are 
especially interesting as furnishing a possible key, in connection with 
meteorological conditions, to the physical changes at greater or less 
depths, which relate to the movements of fishes. 
Aside from the more general subdivision into Gulf Stream and Lab- 
rador current, Prof. Libbey states that two different sets of currents 
have to be dealt with in the study of this region. First are the deep 
currents which flow in two, and generally opposite, directions alongside 
of one another, their courses being controlled more by the mechanical 
influence of the impact of one current upon the other, their relative 
velocities, etc., than by changes in temperature and density. Second 
come the surface currents, which flow in the same general directions as 
the deep ones and are, of course, subject to the same mechanical laws, 
but their courses are additionally affected to a considerable degree by 
the frictional influence of the winds. Moreover, they present a pecu- 
liarity not detected in connection with the deep currents, in that cer- 
tain branches are apparently reversed. The outlying bands of warmer 
and denser water, which pass off from the shore side of the Gulf Stream, 
seem to be drifted toward the shore or away from it to an extent de- 
pendent upon the direction, velocity, and duration of the winds. When 
they are forced toward the shore, thus bridging over the colder cur- 
rents, as they proceed farther and farther from the original source of 
their velocity, they become overpowered. Although retaining much of 
their temperature and density, even to a considerable depth, their 
direction is then sometimes at right angles and finally opposite to their 
first course. 
In connection with this investigation, the surface-towing nets were 
constantly employed, and a large and valuable collection of pelagic | 
