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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 flood, it be more even and level, from the waters returning to 

 their former position, then assuredly, by this decisive instance, 

 the raising of them by a magnetic force can be admitted ; if 

 otherwise, it must be entirely rejected. It is not difficult to make 

 the experiment (by sounding in straits), whether the sea be 

 deeper towards the middle in ebbs, than in floods. But it must 

 be observed, if this be the case, that (contrary to common 

 opinion) the waters rise in ebbs, and only return to their former 

 position in floods, so as to bathe and inundate the coast. 



Again, let the required nature be the spontaneous motion of 

 revolution, and particularly, whether the diurnal motion, by 

 which the sun and stars appear to us to rise and set, be a real 

 motion of revolution in the heavenly bodies, or only apparent 

 in them, and real in the earth. There may be an instance of 

 the cross of the following nature. If there be discovered any 

 motion in the ocean from east to west, though very languid and 

 weak, and if the same motion be discovered rather more swift 

 in the air (particularly within the tropics, where it is more per- 

 ceptible from the circles being greater). If it be discovered 

 also in the low comets, and be already quick and powerful in 

 them ; if it be found also in the planets, but so tempered and 

 regulated as to be slower in those nearest the earth, and quicker 

 in those at the greatest distance, being quickest of all in the 

 heavens, then the diurnal motion should certainly be considered 

 as real in the heavens, and that of the earth must be rejected : 

 for it will be evident that the motion from east to west is part 

 of the system of the world and universal ; since it is most rapid 

 in the height of the heavens, and gradually grows weaker, till 

 it stops and is extinguished in rest at the earth. 



Again, let the required nature be that other motion of revolu- 

 tion, so celebrated amongst astronomers, which is contrary to 

 the diurnal, namely, from west to east and which the ancient 

 astronomers assign to the planets, and even to the starry sphere, 

 but Copernicus and his followers to the earth also and let it 

 be examined whether any such motion be found in nature, or 

 it 1>e rather a fiction and hypothesis for abridging and facili- 

 tating calculation, and for promoting that fine notion of effect- 

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