On Currents in Water. 341 



been accounted for. I therefore asked and obtained permission to 

 forward, for publication, a brief sketch of his theory, which, if 

 it shall be found to be new, and worthy of insertion in the Ameri- 

 can Journal of Science, may hereafter be more fully explained and 

 illustrated, by further extracts from the original letters, in my pos- . 

 session. The following is a brief abridgment and rather free ver- 

 sion of part of his letter. 



If a tub or other vessel be filled with water, and a hole made near 

 to the middle of the bottom to discharge it, the water will acquire a 

 rotary motion from west to south, or opposed to the apparent motion 

 of the sun ; and if means are used to produce an opposite motion, 

 upon withdrawing those means, the former direction will be resumed. 

 This cannot be the effect of chance, but of natural laws, constantly 

 operating. 



Whirlpools appear to be produced by the force of currents, nearly, 

 but not exactly, opposite in direction, for in a vessel of fluid dis- 

 charging at the center of its bottom, gravitation causes the fluid to 

 move from all parts of the circumference towards the center ; and 

 if, in obedience to this law only, the particles all moved directly to- 

 v^ards the center, and met there, there could be no whirlpool, be- 

 cause the currents from the opposite directions would exactly bal- 

 ance each other, and no impulse would be given to produce a whirl- 

 ing or rotary motion ; it would therefore seem to be evident, that 

 the particles of fluids passing from the circumference, and discharg- 

 ing downward at the center, do not move in a direction exactly to- 

 wards the center, and meet there, as in that case no whirlpool would 

 be formed ; whereas it is found by experience, that under common 

 circumstances the rotary motion is always produced. 



The cause producing this effect, I believe to be the rotation of the 

 earth on its axis, which may be explained as follows. 



At the equator, any point P is carried forward in an easterly di- 

 rection, with a greater velocity than any other point P' at any place 

 between the equator and the poles, at which latter places progressive 

 motion entirely ceases. Therefore, if a body at the equator was 

 projected due north, it would only be in case of an instantaneous 

 passage, that the track on the earth, over which it passed, would be 

 a north and south line ; for if time was taken in the passage, it would 

 be in a direction eastwardly of north, inasmuch as the motion east- 

 wardly, which it had at the time of its projection, would continue, 

 and by the composition of forces, the body would move in a direc- 

 tion between north and east. 



