BOOK II.] IKSTAKCfiS OP tflE cr.osi. 507 



but if tlic earth revolves, it may pcrliaps happen, that from the Tin- 

 equal revolution (as regards velocity) of the earth and the waters 

 of the sea, there may be a violent forcin;^ of the waters into a 

 mass, forming the flood, and a subsequent relaxation of them 

 (when they can no longer bear the accumulation), forming Ibo 

 ebb. A separate inquiry must be made into this. Even with 

 this hypothesis, however, it remains equally true, that there 

 must be an ebb somewhere, at the same time that there is a Hood 

 in another quarter. 



Again, let the required nature be the latter of the two motions 

 we have supposed ; namely, that of a rising and subsiding motion, 

 if it should happen that upon diligent examination the pro- 

 gressive motion be rejected. We have, then, three wa3"s before 

 us, with regard to this nature. The motion, by which tlio 

 waters raise themselves, and again fall back, in the floods and 

 ebbs, without the addition of any other water rolled towards 

 Ihom, must take place in one of the three following ways. 

 Either the supply of water emanates from the interior of the 

 earth, and returns back again; or there is really no greater 

 quantity of water, but the same water (without any augmentation 

 of its quantity) is extended or rarefied, so as to occupy a greater 

 space and dimension, and again contracts itself; or there is 

 neither an additional supply nor any extension, but the same 

 waters (with regard to quantity, density, or rarity) raise them- 

 selves and fall from sympathy, by some magnetic power attract- 

 ing and calling them up, as it were, from above. Let us then 

 (passing over the first two motions) reduce the investigation to 

 the last, and inquire if there be any such elevation of the water 

 by sympathy or a magnetic force ; and it is evident, in the first 

 place, that the whole mass of water being placed in the trench 

 or cavity of the sea, cannot be raised at once, because there 

 would not be enough to cover the bottom, so that if there be 

 any tendency of this kind in the water to raise itself, yet it 

 would be interrupted and checked by the cohesion of things, op 

 (as the common expression is) that there may be no vacuum. 

 The water, therefore, must rise on one side, and for that reason 

 be diminished and ebb on another. But it will again necessarily 

 follow that the magnetic power not being able to operate on the 

 whole, operates most intensely on the centre, so as to raise the 

 waters there, which, when thus raised successively, desert and 

 abandon the sides." 



We at length arrive, then, at an instance of the cross, which is 

 this : if it be found, that during the ebb the surface of the 

 waters at sea is more curved and round, from the waters rising 

 in the middle, and sinking at the sides or coast, and if, during a 



■ Bacon's saguclty here foreshadows Newton's theory of the tidei. 



