TIDES. _— 
higher than the solar. It may appear a matter of surprise that the 
sun, which attracts the earth with a force amazingly more . powerful 
than that exerted by the moon, should produce a feebler tide. But 
the reason of this will be apparent when the cause of the tides is 
understood ; it will be then seen that it results from the proximity of 
the moon. 
Let us first inquire into the cause of the solar tide. The sun 
Ba———_>- S$ 
J nenceee cons cen pceceetenne nenee 
Tig. 5. 
attracts the earth with that force which prevents the earth from 
maintaining a straight course ; which bends its path into the vast 
eclipse that the earth sweeps out round the sun every year. It will 
be convenient in the first stage of our inquiry to leave out of con- 
sideration the daily rotation of the earth on its axis. Let then the 
dotted lines of the figure (Fig. 5) represent portions of the annual paths 
which would be pursued by the points 0, 8, and p, if we suppose 
that, instead of a daily rotation, B is kept always turned towards the 
sun. These orbits would be all of them traversed in the same period, 
viz., a year; and they differ slightly in size, the orbit of which Dz is 
a portion being the largest, while ax is the smallest, and B y of 
intermediate size. Now, when orbits of different sizes are thus 
D 
