240 NOVUM ORGANUM 



than sound. We perceive, also, that visible images are re 

 ceived by the sight with greater rapidity than they are dis 

 missed, and for this reason, a violin string touched with the 

 finger appears double or triple, because the new image is 

 received before the former one is dismissed. Hence, also, 

 rings when spinning appear globular, and a lighted torch, 

 borne rapidly along at night, appears to have a tail. Upon 

 the principle of the inequality of motion, also, Galileo at 

 tempted an explanation of the flood and ebb of the sea, 

 supposing the earth to move rapidly, and the water slowly, 

 by which means the water, after accumulating, would at 

 intervals fall back, as is shown in a vessel of water made 

 to move rapidly. He has, however, imagined this on data 

 which cannot be granted (namely, the earth s motion), and 

 besides, does not satisfactorily account for the tide taking 

 place every six hours. 



An example of our present point (the relative measure 

 of motion), and, at the same time, of its remarkable use of 

 which we have spoken, is conspicuous in mines filled with 

 gunpowder, where immense weights of earth, buildings, 

 and the like, are overthrown and prostrated by a small 

 quantity of powder; the reason of which is decidedly this, 

 that the motion of the expansion of the gunpowder is much 

 more rapid than that of gravity, 79 which would resist it, so 

 that the former has terminated before the latter has com 

 menced. Hence, also, in missiles, a strong blow will not 

 carry them so far as a sharp and rapid one. Nor could a 

 small portion of animal spirit in animals, especially in such 



79 The author in the text confounds inertness, which is a simple indifference 

 of bodies to action, with gravity, which is a force acting always in proportion 

 to their density. He falls into the same error further on. Ed, 



