102 Baron N. Schilling on the Constant Currents 



determined by dividing the square of its rotational velocity by 

 the radius of its parallel circle. It thence follows that the cen- 

 trifugal force of the earth is greatest at the equator (0*11124 foot 

 in a second) j and from that to the poles it diminishes in the 

 ratio of the cosines of the latitudes. By its action every thing 

 on the surface of the earth would be thrown off, if the earth's 

 gravitation were not greater than its centrifugal force. Now 

 let us suppose the gravitation of the earth to cease to act during 

 one second. Every particle not firmly adherent to the earth 

 would instantly leave the surface and continue its motion in the 

 direction of the tangent of the corresponding parallel circle with 

 its previous rotational velocity ; and the relative distance of the 

 particle at the end of the second, from its point of separation, 

 which the rotation has meanwhile carried forward on the earth's 

 surface, would serve as an expression of the quantity of the cen- 

 trifugal force of the corresponding parallel circle. 



Thus, if a particle at A (fig. 1) were no longer subject to the 

 earth's gravitation, it would Fig. 1. 



continue its motion in the 

 direction of the tangent 

 AM, and after the lapse 

 of a second would arrive 

 at M instead of at B. A, 

 the point at which it was 

 discharged, would mean- 

 while have reached B ; and 

 B M would denote for us 

 the centrifugal force cor- 

 responding to the parallel 

 circle ABD. Now in 

 reality the action of gravi- 

 tation never ceases, but is 

 constantly directed to the centre of the earth, therefore at a 

 certain angle to the direction of the centrifugal force B M. A 

 freely displaceable particle of the surface would thus, under the 

 action of the two forces, after the lapse of a second not be at M, 

 but would slide on the surface of the earth to F, if there were 

 no friction or other resistance. Every particle of water or air, 

 being free to move, must thus have a tendency to recede from a 

 particle (B) firmly adherent to the earth, and to approach the 

 equator in the direction of the meridian. This tendency is ex- 

 pressed by the quantity BF, which is equal to BM . sin BMF, 

 or the centrifugal force of the parallel circle multiplied by the 

 sine of the latitude. The centrifugal force 





—^s; 





O "^B 





_—- — — — "X"pw 



c 





BM = C.cos0, 



