368 KOVUM ORGAN UAf. 



useless things, or through the multiplication of instruments, or through 

 the mass of materials and of bodies which happen to be required lor 

 any work. Those Instances ought, therefore, to be valued which 

 either direct practice to those points which most concern mankind, or 

 which economize instruments and material. Now the three Instances 

 which refer to this question we call by the general name si Propitious 

 or Benevolent Instances. Of each of these seven Instances we shall 

 now speak separately, and with them conclude that part of our work 

 which relates to the Prerogatives or Ranks of Instances. 



xlv. Among Prerogative Instances we shall put in the twenty-first 

 place, Instances of ike Rod, or of the Radius, which we also call 

 Instances of Carrying through or Non ultra. For the virtues and 

 motions of things operate and take effect in spaces, not indefinite or 

 accidental, but finite and certain ; so that to find and mark these in 

 the investigation of individual Natures is of the greatest importance to 

 practice, not only to prevent errors, but also to render it more exten 

 sive and influential. For we are sometimes allowed to extend these 

 virtues, and, as it were, to diminish their distances, as in the case of 

 telescopes. 



And most virtues operate and affect by manifest contact alone, as 

 is the case in the impact of two bodies, where the one does not remove 

 the other unless the impinging body touches the other. Again, 

 medicines which are applied externally, as unguents, and plasters, do 

 not exercise their virtues without touching the body. Lastly, the 

 objects of the senses of taste and touch do not strike the organs unless 

 they are contiguous to them. 



There are also other virtues which operate at a distance, though a 

 very small one, and of these but a few have hitherto been observed ; 

 they are, however, more than men suspect : as (to take examples 

 from well-known things) when amber and jet attract straws ; one 

 bubble brought near another breaks it ; some purgative medicines 

 draw humours downwards, and the like. But that magnetic virtue 

 which brings together iron and the magnet, or two magnets, operates 

 within a fixed but small circle ; while, on the other hand, if there be 

 any magnetic virtue flowing from the earth (a little below the surface), 

 and affecting the steel needle in its polarity, it must operate at a 

 great distance. 



Again, if there beany magnetic force which operates by sympathy 

 between the globe of the earth and heavy bodies ; or between the 

 globe of the moon and the waters of the sea (which appears highly 

 probable, from the fact of the Spring and Neap tides happening twice 

 a month) ; or between the starry heavens and the planets, by which 

 they are attracted and raised to their apogees ; all these must operate 

 at very great distances. Certain materials are also found which 

 inflame, or catch fire, at considerable distances, as Babylonian naptha 

 is said to do. Heat also insinuates itself at great distances, as also 

 does cold ; so that the inhabitants of Canada feel at a great distance 

 the cold given off by the mounds or masses of ice which breaking 

 loose and floating about the Northern Oc^nn, are carried over the 



