308 Mr. Redfield on the 
therefrom, conjoin to induce a rotary tendency in the incumbent 
winds, in the very direction in which the storms are found to 
revolve.* 
This dynamical tendency to gyration in the atmospheric cur- 
rents or winds which are in contact with the earth’s surface, 
is constantly productive of sensible effects, particularly as we 
proceed from the intertropical to the higher latitudes. This, 
I apprehend, is the chief cause of the changes and variableness 
of the winds in these latitudes, and also of the remarkable in- 
crease of the barometrical oscillations, the great storms being only 
the more strongly marked cases of gyratory action; while the 
numerous weaker or abortive cases which go to fill up the inter- 
vals of space, and partly overlie each other, and which are also 
modified by the ordinary disturbances of temperature and locality, 
have excited little notice or inquiry. It is this law of terrestrial 
rotation which, as I apprehend, is maintained by Prof. Dove of 
Prussia, in his attempts to show the elements of gyration in the 
general winds; a writer with whose labors I have been but lately 
and partially acquainted. 
The general correctness of the foregoing view of the prime 
cause of local gyrations in the atmosphere, as well as the rotation 
in great storms, may be shown by an experiment made on the sur- 
face of acommon globe; which I have occasionally pointed out 
to friends interested in these inquiries. Let a concave surface of 
wood or other substance, of a circular form and a diameter equal 
to five or ten degrees of the globe, be prepared and perforated 
with a small hole in the center, through which a pin may be 
loosely placed, to'serve asan axis. Then let the concavity be 
lined with flannel or other yielding material, and placed upon the 
top of the globe near the equator. ‘Then cause the globe to re- 
volve from west to east in the direction of the earth’s rotation, 
while the concave body is guided, carefully, by the pin at the 
axis, in the direction of the storm tracks which are found on my 
* Tt will be noticed that the rotation of the great storms, as well as more ordi- 
nary atmospheric gyrations, is opposite to that of the great natural circuit of winds 
in which they are carried forward. Thus, ifa general current of revolution swept 
around such a lake as Ontario from left to right, the eddies and local gyrations 
near its borders and in the body of the stream would exhibit a contrary rotation, 
from right to left. 
