16G THE OCEAN. [Book VII. 



aerial currents ; and says tliat against this hypo- 

 thesis it is urged that — 'the air being kept close 

 to the earth by the principle of gravity, would in 

 time acquire the same degree of velocity that the 

 earth's surface moves with, as well in respect of the 

 diurnal rotation as of the annual revolution about 

 the sun, which is about 60 times swifter.' ^ 



Now, in the first place, hypothetically, let every 

 word of this be unreservedly admitted, — and even 

 more — let it not only be said that the air would in 

 time acquire the same degree of velocity that the 

 earth's surface moves with, because it might then be 

 argued that the air has not yet had sufficient time to 

 acquire that degree of velocity, and that therefore 

 vis-inertise, not being yet overcome by gravitation, 

 still causes movements of the air and water — there- 

 fore let it, I say, in the first place be asserted and 

 admitted that the air and water have, and must 

 have, the same degree of velocity that the earth's 

 surface moves with, both in respect to the diurnal 

 rotation and orbital motion, and that the laws of 

 gravitation will not admit of its being otherwise. 



If taken literally, even admitted in this more ab- 

 solute manner, that which is offered as an objection 

 to the possibility of currents being caused by the 

 motion of the earth, instead of being a real objection, 

 would, as far as the axial rotation of the earth is 



1 A Philosophical and Mathematical Dictionary. By Charles 

 Hutton, LL.D. London, 1815. Article, Wind. 



