BOOK II.] INSTANCES OP THE COURSE. 533 



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. 



XLVI. 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 

 ot 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, h 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, 

 according 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 



h We have already alluded, in a note prefixed to the same aphorism 

 of the first book, to Newton s error of the absolute lightness of bodies. 

 In speaking again ot the volatile or spiritual substances (Aph. xl. b. ii.), 

 which he supposed with the Platonists and some of the schoolmen to 

 enter into the composition of every body, he ascribes to them a power 

 of lessening the weight of the material coating in which he supposes 

 them inclosed. It would appear from these passages and the text that 

 Bacon had no idea of the relative density of bodies, and the capability 

 which some have to diminish the specific gravity of the heavier sub- 

 Btances by the dilation of their parts ; or if he had, the reveries in 

 which Aristotle indulged in treating of the soul, about the appetency of 

 bodies to fly to kindred substances, flame and spirit to the sky. and solid 

 opaque substances to the earth, must have vitiated his mind. Ed. 



