NOVUM ORGANUM 439 



The more solid, dry, or compact bodies, such as stones, wood, 

 and metals, admit of much less, and indeed scarcely any percep- 

 tible compression or expansion, but escape by breaking, slipping 

 forward, or other efforts ; as appears in bending wood, or steel 

 for watch-springs, in projectiles, hammering, and many other 

 motions, all of which, together with their degrees, are to be 

 observed and examined in the investigation of nature, either to 

 a certainty, or by estimation, or comparison, as opportunity 

 permits. 



46. In the twenty-second rank of prerogative instances we 

 will place the instances of the course, which we are also wont 

 to call water instances, borrowing our expression from the 

 water hour-glasses employed by the ancients instead of those 

 with sand. They are such as measure nature by the moments 

 of time, as the last instances do by the degrees of space. For 

 all motion or natural action takes place in time, more or less 

 rapidly, but still in determined moments well ascertained by 

 nature. Even those actions which appear to take effect sud- 

 denly, and in the twinkling of an eye (as we express it), are 

 found to admit of greater or less rapidity. 



In the first place, then, we see that the return of the heavenly 

 bodies to the same place takes place in regular times, as does 

 the flood and ebb of the sea. The descent of heavy bodies 

 towards the earth, and the ascent of light bodies towards the 

 heavenly sphere, take place in definite times, according to the 

 nature of the body, and of the medium through which it moves. 

 The sailing of ships, the motions of animals, the transmission of 

 projectiles, all take place in times the sums of which can be 

 computed. With regard to heat, we see that boys in winter 

 bathe their hands in the flame without being burnt ; and con- 

 jurers, by quick and regular movements, overturn vessels filled 

 with wine or water, and replace them without spilling the liquid, 

 with several similar instances. The compression, expansion and 

 eruption of several bodies, take place more or less rapidly, ac- 

 cording to the nature of the body and its motion, but still in 

 definite moments. 



In the explosion of several cannon at once (which are some- 

 times heard at the distance of thirty miles), the sound of those 

 nearest to the spot is heard before that of the most distant. 

 Even in sight (whose action is most rapid), it is clear that a 

 definite time is necessary for its exertion, which is proved by 

 certain objects being invisible from the velocity of their motion, 

 such as a musket-ball ; for the flight of the ball is too swift to 

 allow an impression of its figure to be conveyed to the sight. 



This last instance, and others of a like nature, have sometimes 

 excited in us a most marvellous doubt, no less than whether the 

 image of the sky and stars is perceived as at the actual moment 



