208 Transactions. 



of experiment. A stream running 1 ft. a second is, we suppose, 

 able to move a stone 2 lb. 'u\ weight. Increase the velocity 

 to 2 ft. a second : instead of now being able to hft a stone 2 lb. 

 in weight, it can lift one of actually 64 lb. weight, 64 being 2^. 



Now, consider these accunmlated facts : The effects of 

 the terrestrial rotation are unceasing and cumulative. It is 

 allowed to cause a)i extra pressure on the left bank ; it is al- 

 lowed to increase depth of water and so increase the velocity 

 on left bank ; it is allowed, in a river of the rate of flow and 

 S. latitude (altogether neglecting the size) of the Mississippi, to 

 cause a selective motion of velocities towards left bank of curves 

 of 9 per cent., and then the transporting-power of stream varies 

 as sixth power of velocities, so that even if the velocity on the 

 left bank be very slightly greater the difference in corroding- 

 power will|be very appreciable. Consider these accumulated 

 facts, and we may believe that the rotation of the earth may 

 well have some slight effect on the course of a river — slight, 

 of course, is agreed, but not so slight as to be unappreciable in 

 favourable circumstances. 



Gilbert, in the paper mentioned above, describes an actual 

 case where he believed that the terrestrial rotation had most 

 evidently determined the course of several streams. On the 

 south side of Long Island, New York, a number of streams flow 

 doAvn a plain of gentle slope and essentially homogeneous for- 

 mation. Each of these valleys is bordered on the right side by 

 a bluf? from 10 ft. to 20 ft. high, while its gentle slope of the 

 left^^side merges imperceptibly with the general plain. The 

 •stream in each case follows closely by the bluff at the right, and 

 there seems no reasonable doubt that these peculiar features 

 result from the influence of terrestrial rotation. 



Thus much I read at a time when I had seen the Canterbury 

 rivers only while crossing them on the main line of railway. But 

 thinking over them, I remembered that the Rangitata and Wai- 

 taki had steep and high banks on tlieir left sides, and very 

 sloping or unnotioeable banks on their right. I also thought then 

 that the Canterbury Plains were homogeneous in stmcture, and 

 had several streams running across them, so that if the rotation 

 of the earth did have a deflecting influence on the courses of 

 rivers, we should on those plains see it as well as anywliere. 

 To be able to detect the influences of the earth's rotation we need 

 an even' slope through a homogeneous structure. Where rocks 

 of different hardness occur, or where the slope is not regular, 

 we can expect the influence of the earth's rotation to be partially 

 or whollv obscured. I started a year ago to take measurements 

 of the height of the4)anks of the rivers, and the distance of these 

 banks from the right and left pide of the stream. In the course 



