ELECTRICITY. 



CHAPTER I. 

 General Facts and Principles. 



(1 .) THE science of ELECTRICITY, which 

 now ranks as one of the most important 

 branches of Natural Philosophy, and 

 which embraces so many subjects of 

 inquiry, exceedingly curious in them- 

 selves, and highly interesting from their 

 relations with" every department of na- 

 ture, is wholly of modern creation. The 

 ancients were, indeed, acquainted with 

 a few detached facts, depending on the 

 agency of electricity; such as the at- 

 tractive power which amber acquires by 

 being rubbed, the benumbing shocks 

 which are experienced on touching the 

 torpedo (or electrical eel), and the ap- 

 pearance of those sparks or streams of 

 light which, on some occasions, are seen 

 to issue from the human body. But no 

 suspicion was entertained that these 

 phenomena had any connexion with one 

 another ; and far less was it imagined 

 that they were the effects of a power 

 pervading all material bodies, and ex- 

 tensively concerned in all the operations 

 of nature. 



(2.) It was only by slow degrees that 

 this knowledge was acquired. The first 

 step towards a generalization of the 

 phenomena was made by Dr. Gilbert, 

 an English physician, who, in the year 

 1GOO, published a very original and va- 

 luable treatise on the magnet. He re- 

 marked th -it several other bodies besides 

 amber can, by friction, be made to at- 

 tract light bodies ; and he was thus led 

 to the discovery of a property common 

 to all of them. The Greek name for 

 amber being Xxr S ay (Electron), the 

 bodies possessed of this property were 

 denominated Electrics; and the "power 

 they manifested was termed ELECTRI- 

 CITY. The observations of Boyle, Otto 

 Guericke, Newton, and a lew other phi- 

 losophers of the same period, contributed 

 somewhat to the extension of our know- 

 ledge on this curious subject ; but even 

 the information collected during the 

 whole of that century amounted to 

 nothing that could be- entitled to the 



name of science. The real science of 

 Electricity can, properly speaking, be 

 considered as taking its rise only in a 

 later age ; and it was the first fruit of 

 that active spirit of investigation, which 

 at the commencement of the eighteenth 

 century was rapidly diffusing itself over 

 Europe. The establishment of the Royal 

 Society of London appears to have had 

 considerable influence in promoting the 

 cultivation of electricity: for we find 

 that almost every discovery of import- 

 ance in this science was made by the 

 members, and is recorded in the Trans- 

 actions of that Society. But it was not 

 until the present century that the ex- 

 tensive relations which connect electri- 

 city with so many other branches of 

 physical science, were discovered, and 

 their importance appreciated. Already 

 have we seen, in this short era, the rise 

 of a new science, founded on that pe- 

 culiar modification of Electricity, which 

 is known by the name of GALVANISM. 

 Hence, have we derived new instru- 

 ments of analysis, new paths of research, 

 and new powers of extending the- do- 

 minions of science; hence, have we 

 been able to trace alliances between 

 several of the great agents concerned 

 in the phenomena of the material uni- 

 verse. ELECTRO-CHEMISTRY has thus 

 arisen as one of the connecting branches 

 between remote divisions of the Philo- 

 sophy of Nature. Still more recently 

 there has been opened to us, in the sub- 

 ject of ELECTRO-MAGNETISM, another 

 new province of science, which esta- 

 blishes a natural connexion between 

 two powers hitherto regarded as dis- 

 tinct. 



So rapid has been the march of scien- 

 tific improvement, that it is difficult for 

 those whose attention has not been 

 steadily and exclusively devoted to these 

 particular objects, to keep pace with 

 the progress of discovery. The mate- 

 rials collected by the numerous labourers 

 in these wide fields of inquiry have 

 poured in upon us so fast, that there 

 has scarcely yet been time for marshal- 

 ling them in their proper places, and for 



