LET. VIII. pF THE NATURE OF THE Tfl^ES. I37

have the precise situations here mentioned; be-cause, in this cafe, as in ail others, the actions donot produce the greatest effect when they are thestrongest, but some time afterwards.

The effects of the disturbing forces of the supand moon, depend, likewise, upon their respec-tive distances from the earth, as well as upontheir particular situations. For the less thedistances are, the greater will be the effects;and, therefore, in winter, when the fun is nearerto the earth, the spring tides will be greater thanin summer, when he is farther off; and theneap tides, on that account, will be less. And,for a like reason, as the moon moves in apelliptical orbit round the earth, and is nearer tous at some times than at others, the tides will,at those times, be greater, and at the oppositepoints of her orbit less. Some variations, like-wise, take place in consequence of the differentdeclinations of the fun and moon at differenttimes. For if either of these luminaries wereat the pole, it would occasion a constant eleva-tion both there and at the opposite one, and aconstant depression at the equator; so t-hat a?the sun and moon gradually decline from theequator, they lose their effect, and the tidesbecome less; and when they are both in theequator, the tides of course become greater.

These are the principal phænomena of thetides; and where no local circumstances inter-fere.