192 THE MECHANICO-CHEMICAL SCIENCES. 



piece of amber when rubbed. Such results are altogether different 

 from the universal attraction which, according to Newton's discovery, 

 prevails among all particles of matter, and to which cosmical pheno- 

 mena are owing. But yet the difference of these special attractions, 

 and of cosmical attraction, Avas at first so far from being recognized, 

 that the only way in which men could be led to conceive or assent to 

 an action of one body upon another at a distance, in cosmical cases, 

 was by likening it to magnetic attraction, as we have seen in the 

 history of Physical Astronomy. And we shall, in the first part of out 

 account, not dwell much upon the peculiar conditions under which 

 bodies are magnetic or electric, since these conditions are not readily 

 reducible to mechanical Jaws; but, taking the magnetic or electric 

 character for granted, we shall trace its effects. 



The habit of considering magnetic action as the type or general 

 case of attractive and repulsive agency, explains the early writers 

 having spoken of Electricity as a kind of Magnetism. Thus Gilbert, 

 in his book De Magnets (1600), has a chapter, 1 De coitions Magnitica, 

 primiimque de Succini attractions, sive verius corporum ad Succinum 

 applications. The manner in which he speaks, shows us how myste- 

 rious the fact of attraction then appeared ; so that, as he says, " the 

 magnet and amber were called in aid by philosophers as illustrations, 

 when our sense is in the dark in abstruse inquiries, and when our rea- 

 son can go no further. Gilbert speaks of these phenomena like a 

 genuine inductive philosopher, reproving 8 those who before him had 

 " stuffed the booksellers' shops by copyiag from one another extrava- 

 gant stories concerning the attraction of magnets and amber, without 

 giving any reason from experiment." He himself makes some im- 

 portant steps in the subject. He distinguishes magnetic from electric 

 forces, 3 and is the inventor of the latter name, derived from jjXsxrpov, 

 electron, amber. He observes rightly, that the electric force attracts 

 all light bodies, while the magnetic force attracts iron only ; and he 

 devises a satisfactory apparatus by which this is shown. He gives 4 a 

 considerable list of bodies which possess the electric property ; " Xot 

 only amber and agate attract small bodies, as some think, but diamond, 

 sapphire, carbuncle, opal, amethyst, Bristol gem, beryl, crystal, glass, 

 glass of antimony, spar of various kinds, sulphur, mastic, sealing-wax," 

 and other substances which he mentions. Even his speculations on 

 the general laws of these phenomena, though vague and erroneous, as 



1 Lib. ii. cap. 2. " De Magnete, p. 4S. 3 Ib. p. 52. 4 Ib. p. 48. 



