CORRESPONDENCE ON SOME PROBLEMS CONNECTED WITH RIVERS & CANALS.

Abstract

JfI Alford. flowing 'vl'est, the water, moving more slowly than the banks, had a tendency to move towards the pole, and pressure occurred between the polar or right bank and the water.In the southern hemisphere similar causes produced pressure on the left bank. Rivers which were not flowing towards one of the cardinal points of the compass partook of both influences. Professor W. Ferrel's writings dealt with the subject, principally in regard to the movements of atmospheric air, but his conclusions applied also to rivers. and were generalized so as to apply to all rivers, what~ever the direction. The pressure per square foot of river-bank was pro-1)ortional t.o t,he breadth of the rivcr, t o the velocity of the water, ant1 t u the sine of the anglc of lat,itude. The greatest effect, dealing only with that aspect of the force. was t,o be expected in large rivers i n high latitudes ~v h e n in flood. Indian rivers, 011 account of their low latitudes, were not likely to be conspicuons examples. The case of t.he Colorado river breaking int,o the Salton sea was pointed out by Mr Lacey, but Mr. ltothery, \v110 referred in detail t,o the break-through, did not mention the earth's rotation as a cont,ributory cause. To find the effect a t its greatest it, would seem necessary to turn to the great Siberian rivers. The Yenesei reached the sea about latitude 7 3 degrees. Dr. F. Kansen, in his book on Siberia,' describing his journey up the Yenesei, the deep-water channel of which was on the right or eastern side, referred to the remarkable difference between the right and left banks of the river, and stated that there was no getting away from t,he conclusion t,hat such was due to the earth's rotation.Dr. Nansen regarded the gcological structure as being a n additional factor. The question had been asked, Why, if the theory was true, was not a larger area of alluvium found on the left than on the right bank of rivers of the northern hemisphere ? Some rivers in relatively low latitudes did show that characteristic. The reason why it was lacking on others might be the folloR-ing :-Forces which tended to cause excess pressure against one bank also tended to direct towards that bank all silt being carried dowl the rirer, the specific gravity of whicJ1 was greater than 1.0. The latter action made for accret'ion, while the former was erosive. M7het,her tlte resultant sum was plus or minus would appear to depend on the circumstances of each case, and particularly on the quantity and nature of the silt brought down by floods. The deflection of the silt was an influence superimposed ou ' "