i88 3 .] 
Relations between Earth and Moon. 
453 
I "*~ 2978 
days 
after the other, in conformity with the lunation, except a 
difference of 1-3546 of a day, the square of the excentricity 
of the common orbit of moon and earth, and the twofold 
excentricity of the earth itself. But the former tides occur 
39 minutes and the latter 75 minutes later, times which 
stand in the same relation as the greatest and least tide at 
any place, the sun being in one case an increasing and acce- 
lerating, in the other a diminishing and delaying, power. 
The time of flood after culmination is therefore always 
longer in higher than in lower latitudes, because the differ- 
ence in distance through latitude and the distribution of 
gravity on the earth tell more against the absolutely nearer 
moon, with her smaller mass, than against the more distant 
larger sun. 
The greatest flood on each day falls in the mean 3*24 
hours after the upper or lower culmination of the moon, 
but during the syzigies 378, and during the quadratures 
270, later. The reason of the delay is not that the water 
requires time to collect, for an attracting force will lift as 
much from where it is going to as from where it comes from 
if the attracted substance is equally distributed round the 
attracting force. The cause is that the attracted substance 
is not equally distributed, the surface of the earth being 
composed of— 
parts 
3*83 r 
of yielding, waving liquid, and — 
5% p* ct 
of arresting, resisting solid, unequally distributed, divided 
by moving rings of the liquid, the ocean. The time from 
tide to tide is 12*41 hours, and— 
12*41 h. 
3*^3 
3*24 h. 
The greatest height of the tide will, however, in the mean 
fall not more than 3 hours after culmination of the moon, 
the inclination t>f the ocean rings to the meridian causing 
by lateral pressure an acceleration of 1-12*08, reducing the 
3*24 hours to 3, the extent of the polar zones being 1-12*08 
of the sphere. 
