20 



Since they lie between adjacent isobaric surfaces their continuation 

 must cease only by turning on themselves or by meeting the sides 

 of the basin. V. Bjerknes has given the name "solenoid" to an 

 isobaric-isosteric tube. It is convenient to select as a unit tube one 

 included by isosteric surfaces constructed for intervals of 10~^ of 

 specific volume, and isobaric surfaces constructed for intervals of 

 one centibar. Bjerknes has also called attention to the significance 

 of solenoids by stating that the measure of the intensity of forces in 

 a given vertical sectional area is in direct proportion to the number 

 of solenoids running through it. This number depends upon the 

 degree of stability and inclination; the greater the stability and the 

 inclination, the greater the number of solenoids per unit cross- 

 sectional area. 



EFFECT OF EARTH ROTATION ON OCEAN CURRENTS 



Dynamic tendencies of water particles have been discussed purely 

 as indicated by mass distribution; now the behavior of such phenom- 

 ena are traced in the form of actual motion on, and as qualified by, 

 the veering surface of a rotating sphere. 



In order to understand the effect of earth rotation on currents, 

 we might begin by studying very closely the absolute movement of 

 a fixed body at the pole of a rotating sphere and another similar 

 body on the equator. It will soon be perceived that the former 

 enjoys a pure centric movement while the latter has a pure transla- 

 tory motion, and any intervening point partakes a centric-transla- 

 tory path. Bodies at rest relatively to the globe, as also the surface 

 of the earth itself, are, strictly speaking, under a phase of centric 

 and translatory motion, the relation between the two depending upon 

 the geographical latitude. This phenomenon is very difficult to 

 comprehend, since all of our senses are trained to accept the earth 

 and resting bodies as a stationary base, and these remarks in so 

 short a space, can hope to touch generalities only. Those who are 

 interested in a detailed exposition of the subject are referred to 

 Krummel (cf., Handbuch der Ozeanographie, vol. 2). Also Humph- 

 reys (cf., " Physics of the Air." 1920). 



As long as all bodies remained in fixed relations, a state of "rest" 

 may be said to prevail, by virtue of the fact that no variations from 

 the relative positions exist. But distinction immediately arises 

 whenever any free motion whatsoever, relatively to the earth, is 

 introduced. At any other point on the earth's surface than along 

 the equator, due to the element of centricity previously described, 

 divergence takes place between the straight path of a particle due 

 solely to inertia, and the movement of other particles held fast to 

 the surface of the earth and carried around with it as it rotates. 

 This fact was proven years ago when the straight line of motion 

 possessed by Focault's pendulum swinging to and fro soon revealed 



