GENERAL MEETING. a8 
curvature of about 13 miles. Centrifugal force being a simple in- 
verse function of radius of curvature, it follows that the deflective 
force by which the river is impelled toward its right bank by virtue 
of rotation is proportioned to the force by which it is impelled 
toward its outer bank on acute bends in the ratio of 13 to 20. That 
is to say, in this particular instance -the rotational deflective force 
is 73 per cent. of the deflective force from curvature of channel. 
The process of lateral corrasion isso complex that it is impossible 
to convert this result into terms of erosion and consequent deflec- 
tion of stream channel, but a consideration of the manner in which 
the two deflective forces are combined sufficiently indicates that that 
due to rotation cannot be ignored. Wherever the stream bends 
toward the left the centrifugal force developed by the curvature is 
augmented by the rotational force; wherever the stream turns to- 
ward the right the centrifugal force is diminished by the amount of 
the rotational force; so that the tendency of the swiftest threads of 
current to approach the outer bank must be notably greater in one 
set of bends than in the other. } 
If this analysis of the subject is legitimate, the rotation of the 
earth ought surcly to modify the courses of rivers to such extent 
that the modifications are observable phenomena. Exception should 
however be made of two important cases: first, rivers which are 
rapidly deepening their channels are by that fact held rigidly to 
their original courses, and are not deflected either by rotation or 
by any other cause; second, those parts of rivers whose function 
is deposition instead of erosion, should theoretically, under the 
influence of rotation, built their alluvial plains higher on the right 
hand side than on the left, and having established an inclination 
of the alluvial plain toward the left, should thereafter meander 
over the plain with ‘equal facility in all directions. It is only in 
the. middle courses of streams, where the work performed by the 
water is chiefly that of transportation, that the discovery of the 
effects of rotation should be expected. 
Mr. Warp remarked that in the regions especially discussed the 
river courses are, in general, southerly, while the prevailing winds 
are westerly, so that the influence of the winds is opposed to what- 
ever influence may be exerted by rotation. Mr. ABBE said that 
the tendency of driftwood toward certain river banks, cited by 
