AMERICAN JOURNAL OF SCIENCE. 
[THIRD SERIES.] 
Arr. XLIX.—The Sufficiency of Terrestrial Rotation for the 
Deflection of Streams; by G. ILBERT. 
[Read to the National Academy of Science, April 15, 1884.] 
It was long ago perceived that rivers flowing to the north or 
to the south should by the rotation of the earth be thrown sev- 
erally against their east or west banks. It is even many years 
Since it was shown by Ferrel that these tendencies are but 
illustrations of a more general law, that all streams in the 
northern hemisphere are by terrestrial rotation pressed against 
their right banks, and all in the southern are pressed against 
their left banks, the degree of pressure being independent of 
the direction of flow. Yet the question of the sufficiency of 
the cause for the production of observable modifications in the 
topography of stream valleys is still an open one. A number 
of geologists have observed peculiarities of stream valleys 
which they referred to the operation of the law, while others, 
including myself, have looked in vain for phenomenal evidence 
of its efficiency. Nevertheless, it is my present purpose to 
maintain the sufficiency of the cause. | 
ar as I am aware, all those who have attempted to con- 
sider analytically, the mode in which the lateral tendency 
arising from rotation should modify the channel or valley of a 
Stream have reached the conclusion that no appreciable . 
results can be produced, and for the most part their conclusions 
legitimately follow their premises. own different conelu- 
Sion is based upon an essentially different analysis of the 
Am. Jour. oe Series, Vou. XXVII, No. 162.—Jonz, 8 
