J. R. Mayer on Celestial Dynamics. 399 
to worn Sire tidal wave produces a general westerly current in 
the o 
This « Pret is opposite in direction to the earth’s rotation, 
and therefore its friction against and collision with the bed and 
shores of the ocean must offer stirs where resistance to the axial 
rotation of the earth, and diminish the vis viva of its motion. 
The earth here plays the part of a fly-wheel. The movable 
parts of its surface adhere, so to speak, to the relatively fixed 
moon, and are dragged in a direction opposite to that of the 
earth’s rotation, in consequence of which, action takes place be- 
tween the solid and liquid parts of this fly- -wheel, resistance is 
overcome, and the given rotatory effect diminishe 
Water-mills have been turned by the action of the tides ; ri 
effects produced by such an arrangement are distinguished | in 
remarkable manner from those of a mill turned by a sa 
stream. The one obtains the vis viva with which it works from 
the earth’s rotation, the other from the sun 
arious causes combine to incessantly maintain, partly i in an 
undulatory, partly in a progressive motion, the waters of the 
ocean. teats the influence of the sun and ‘the moon on the ro- 
‘Ocean likewise exercise a manifold influence on the velocity, di- 
rection, and extent of the oceanic currents 
The motions in our atmosphere, as well as those of the ocean, 
presuppose the existence and consumption of vis viva to over- 
come the continual resistances, and to prevent a state of rest or 
equilibrium. Generally speaking, the power necessary for the 
production of aérial currents may be of threefold origin. Either 
the radiation of the sun, the heat derived from a store in the in- 
terior of ~ earth, or, lastl y, the rotatory effect of the earth may 
the source. 
As Ai as quantity is concerned, the sun is by far the most 
important of the above. According to Pouillet’s measurements, 
asquare metre of the earth’s surface receives on the average 
4-408 units of heat from the sun per minute. Since one unit of 
‘vis viva equal to 1620 Km, or + tis whole of the earth’s surface 
‘in the same time 825,000 billions of Km. A power of 75 Km 
‘per second is called a horse-power. A roid to this, oxy — 
of the solar radiation in oe work 0 nd te ae 
3 the earth’s surface would be equal to 0'36, “id the total | 
fect for the whole globe 180 billions of horse- not 
Giconsiderable portion of this enormous quantity bape vis viva is 
