372 NOVUM ORGANUM. 



in the diurn.il motion, (which has so astonished grave men, that they 

 preferred believing that the earth moved), makes that motion of 

 radiation (although, as we said, marvellous in its quickness) more 

 credible. But the consideration which moved us most of all was that 

 if any perceptible interval of time were interposed between the real 

 and the apparent, it would happen that the appearances would often 

 be intercepted and confused by rising clouds, and similar disturbances 

 of the medium. And now sufficient has been said about the simple 

 measures of time. 



But we have not only to seek the simple measure of motions and 

 actions, but, what is much mere important, their comparative measure, 

 for that is of immense use and of wide application. We see that 

 the flash of a gun is seen sooner than its report is heard, although 

 the ball must necessarily strike the air before the flame behind it 

 can get out ; now the cause of this is, that the motion of light takes 

 place more rapidly than that of sound. We see also, that visible 

 images are taken up by the sight more quickly than they are dismissed ; 

 whence it happens that the strings of a fiddle, struck by the finger, are 

 doubled and trebled in appearance, because a new image is received 

 before the old one is dismissed ; so it also happens that revolving 

 rings assume a spherical appearance ; a blazing torch carried hastily 

 at night seems to have a tail. Also upon this inequality of motions, 

 as regards velocity, Galileo built up his theory of the flowing and 

 ebbing of the sea ; imagining that the earth revolved faster than the 

 waters, whence the waters gathered themselves up in a heap, and 

 then in turn relaxed and fell, as is shown in the case of a vessel of 

 water moving quickly. But for this speculation he demands data 

 which cannot be allowed (viz. that the earth moves), and besides we 

 have not sufficient information as to the tidal motion of the ocean 

 every six hours. 



But we have a conspicuous example of the matter in hand, namely, 

 of the comparative measures of motions, and not only of the thing 

 itself, but also of its singular use (of which we spoke a little while ago) 

 in mines charged with gunpowder, whereby vast masses of earth, 

 buildings, and the like, are upheaved and thrown into the deep by an 

 insignificant quantity of powder. The cause of this undoubtedly is, 

 that the expanding motion of the powder, which is the impelling 

 force, is many times quicker than the motion of gravity, which resists 

 it ; so that the former motion is accomplished before the opposing 

 motion begins, and thus at the outset the resistance is a nullity. 

 Hence it is not the strong blow, or the sharp and rapid one, which is 

 most effective in projecting all kinds of missiles. Nor would it be 

 possible that the small quantity of animal spirit in animals, especially 

 in such vast bodies as those of whales, or elephants, could lead and 

 govern such a large mass of body, were it not for the velocity of the 

 motion of the spirit, and the slowness of the bodily mass in exciting 

 its resistance. 



Indeed, this is a principal foundation of the experiments in magic, 

 about which we shall speak presently, where a small mass of mattqr 



