92 Transactions. — 'Miscellaneous. 



belonged to tlie invaders and wliicli to the invaded. I have classed the 

 allies, hapiis. and sections of hapus of each tribe under one common 

 appellation : Maoris may say I am wrong, but I appeal from them to 

 the common sense of my English readers, and am hopeful of then* verdict 

 in my favour. 



Art, VI. — On the Influence of the Earth's Eotatiou on Rivers. 

 By A. C. Baines. 

 [Head before the PldlosopMcal Institute of Canterbury, 4:th October, 1877.] 

 In his address to this Institute, delivered on April 5th, 1877, Dr. von 

 Haast devotes some space to the explanation of the important fact that 

 rivers, whose banks are composed of loose materials, wear away their right 

 banks in the northern hemisphere and their left in the southern, at the 

 same time building up the opposite banks. 



Dr. von Haast gives an account of the theory of Von Baer, who first 

 showed that the observed changes in the courses of rivers might be 

 explained as a consequence of the earth's rotation. Von Baer's explanation 

 depends upon a well known mechanical theorem, by which the westward 

 motion of the trade winds had previously been accounted for, and which 

 may be thus stated- — " A body moving on a meridian tends to be deflected 

 towards the right in the northern hemisphere, and towards the left in the 

 southern, in consequence of the change in its eastward velocity as it 

 axiproaches or recedes from the earth's axis." The change in the eastward 

 velocity, it is necessary to observe, accounts for only a part of the deflecting 

 force. The direction of motion in space is also changing as the earth 

 revolves. A railway truck moving on a meridian in the southern hemis- 

 phere has its line of motion turned round in the same direction as that of 

 the hands of a watch. There must consequently be a i^ressure against the 

 truck towards the right, and an equal pressure against the rails towards the 

 left, which must be added to that caused by the change of eastward velocity. 



The explanation given by Von Baer does not account for the fact that 

 where the course of a river is east and west the banks are worn away in the 

 same manner as where the course is on a meridian. To explain this it must 

 be shown that a body moving at right angles to the meridian tends to be 

 deflected. 



A body resting on the earth's surface, and free to move in any direction 

 upon it, is maintained in equilibrium by attraction directed towards the 

 earth's centre, and centrifugal force directed away from the axis. If the 



