NOVUM ORGANUM. 151 



force can be admitted, if otherwise, it must be entirely re 

 jected. 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 ob 

 served, if this be the case, that (contrary to common opinion) 

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

 sition 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 perceptible 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 dis 

 tance, being quickest of all in the heavens, then the diurnal 

 motion should certainly be considered as real in the hea 

 vens, 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 

 revolution, 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 be rather a fiction and hy 

 pothesis for abridging and facilitating calculation, and for 

 promoting that fine notion of effecting the heavenly motions 

 by perfect circles. For there is nothing which proves such 

 a motion in heavenly objects to be true and real, either in 

 a planet s not returning in its diurnal motion to the same 

 point of the starry sphere, or in the pole of the zodiac being 

 different from that of the world, which two circumstances 

 have occasioned this notion. For the first phenomenon is 

 well accounted for by the spheres overtaking or falling be 

 hind each other, and the second by spiral lines, so that the 



