766 T. C. CHAMBERLIN 
into the Mississippi Valley, where they curve about and follow 
the courses shown on Hann’s chart. These courses seem to fall 
into two classes, the one running spirally inward toward the center 
of the great fixed eddy, the other spirally outward with dispersive 
tendencies. A suggestion relative to the possible reason for 
this last feature will be given in another connection. 
A more general view.—While all generalizations now enter- 
tained must be held very tentatively, because of the imperfection 
of present data, a general conception of the circulation of the 
northern part of the northern hemisphere, which will serve to 
bring together and give coherence and unity to the more special 
features which have been discussed, may be pardoned. 
The whole temperate and polar region is divisible into areas 
of high pressure (annual average above 29.95 inches, 760 mm) 
in which the dominant currents are downward and outward, and 
areas of low pressure (annual average below 29.95 inches, 760 
mm) in which the dominant currents are inward and upward. 
The mutual disposal of these gives a basis for a general view of 
the atmospheric circulation. 
The high pressure loop.—tIn tracing the former we may start, 
for convenience, on the 30° latitude tract at its Atlantic node 
near the Azores, where it les between 30° and 40° north latitude. 
Tracing it thence easterly, it inclines notably to the north, and 
at the meridian of 100° east, has made a northerly gain of 20° 
latitude. Thence onward it continues to gain in latitude, at 
first more rapidly and then less rapidly to about the meridian 
of 180°, when its course is nearly normal to the meridian, and 
its latitude may be roughly taken as 75°. Thence onward its 
course is south of east to the Mackenzie basin, and thence more 
southerly over the Canadian plains east of the Rocky Mountains 
until it again joins the high tract that normally lies near 30° 
latitude. It thus makes a great loop swinging around the pole, 
and passing near it at its climax in latitude, and enclosing the 
great north Atlantic eddy (see sketch map 2). The tract is 
accentuated by nodes of an anticyclonic nature. The chief of 
these is the great “high? of Asia) (Whis prothudesmtom tite 
