4'76 Dr. R. Hare's Objeclio7is to the Theories severally of 



batteries, is inconsistent with that accumulation of oethereal 

 polarity which constitutes a statical spark-giving charge. 



50. As all the members forming a voltaic series have to be 

 discharged in one circuit, the energy of the effort to discharge, 

 and the velocity of the consequent undulations must be, ceteris 

 paribus, as the number of members which co-operate to pro- 

 duce the discharge. Of course the more active the fethereo- 

 ponderable waves, the greater must be their efficacy in pro- 

 ducing asthereal waves of polarization as a secondary effect, 

 agreeably to the suggestions above made (49, 36). 



51. Hence in a battery consisting of one galvanic pair ex- 

 cited by reagents of great chemical energy and conducting 

 power, the electro-magnetic effects are pre-eminent ; while 

 De Luc's electric columns consisting of several thousands of 

 minute pairs, feeble as to their chemical and conducting effi- 

 cacy, are pre-eminent for statical spark-giving power (48). 

 This seems to be quite consistent, since on the one hand, the 

 waves of polarization must be larger and slower, as the pairs 

 are bigsfer and fewer : and on the other hand smaller and 

 more active, as the pairs are more mmute and more numerous. 



On the perfect similitude between the Polarity communicated 

 to Iron Filings by a Magnetized Steel Bar, and a Galvanized 

 Wire. 



52. If by a sieve, or any other means, iron filings be duly 

 strewed over a paper resting on a bar magnet, they will all 

 become magnets, so as to arrange themselves in rows like 

 the links of a chain. Each of the little magnets thus created, 

 will, at its outermost end, have a polarity similar to that of 

 the pole (of the magnet) with which it may be affiliated. Of 

 course the resulting ferruginous rows formed severally by the 

 two different poles of the bar, will have polarities as opposite 

 as those of the said poles. 



53. In an analogous mode, if two wires be made the media 

 of a galvanic discharge, ii'on filings, under their influence, will 

 receive a magnetic polarity, arranging themselves about each 

 wire like so many tangents to as many radii proceeding from 

 its axis ; those magnetized by one wire reacting with such 

 as are magnetized by the other. 



54. The affections of the ferruginous particles during the 

 continuance of the current so called, are precisely like those 

 of the same particles when under the influence of the bar 

 magnet. The great discordancy is in the fact, that the influ- 

 ence of the magnet is permanent, while that of the wire is in- 

 debted for existence to a series of oppositely polarizing but 

 transient impulses which proceed towards the middle of the 



