540 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



He found that if the junction of two dissiniiU\r metals wore heated, an elec- 

 trical current would flow from one to the other. From this form of electri- 

 city we may expect in time important results, and though in this mode of 

 electricity the currents are weak, still, in my opinion, investigations pur- 

 sued in this direction will develop means to strengthen them. It may not 

 be uninteresting to recall to mind the lengtlw discussion carried on between 

 Galvuni and Volta. The former was of opinion that a peculiar fluid was 

 secreted in the brain, which was sent along the nerves to all the diflferent 

 parts of the body; that the muscles were capable of being charged with it, 

 and that convulsions produced in the muscles were produced by a discharge 

 of the nervous energy from the muscle, in consequence of the conducting 

 power of the metals. Volta was of a different opinion, and argued that 

 these conditions were produced by the passage of a current of common 

 electricity through the linib of the frog, which was thrown into a state of 

 convulsions merely in consequence of its irritability. 



The Franklinian theory of one electricity, though popularly received and 

 acted upon, fails to explain with entire satisfaction some peculiarities of 

 electrical phenomena. For example, two balls, resinously or negatively 

 electrified, repel each other. 



Cavendish and Epenius, in explaining this, supposed all particles to repel 

 each otiier without electricity. There are three epochs in the history of 

 electro-magnetism. The first being that of Galvani and Volta's discussions; 

 the second Profs. Oersted, Henry and Faraday's discoveries; and the third 

 the developments of the electro-magnetic telegraph. About twenty j'eara 

 regularly intervened between these successive steps. 



All telegraphic machines are so many electro-magnetic engines, the force 

 or power-producing apparatus being situated many miles from the engine, 

 and a mine employed to carry the moving agent precisely as a tube would 

 be employed if compressed air, carbonic acid or other gas were used in the 

 place of electricit3\ No encouraging success has yet attended the attempts 

 to employ electricity as an economic power. Wlien we reflect on the cost 

 of the coal used to produce power by steam, and the cost of zinc to gene- 

 rate power by electricity, the advantage is much in favor of the coal. 



By instituting a comparison between the different means of producing 

 power, it has been shown that for every shilling expended there might be 

 raised: 



By manual power, 600,000 pounds one foot high in a day. 

 By horse power, 3,600,000 do do do 



By steam power, 56,000,000 do do do 



By electro-magnetism, 900,000 do do do 



Electro-metallurgy is of much more industrial importance than would be 

 supposed by a casual observer. If the number of persons employed in 

 electro silver-plating, deposition of copper, and electro-stereotyping in this 

 city were named, there are few present who would not be surprised. At 

 Birmingham, England, 500 operatives were employed a short time since in 

 one factory. 



Electricity as a remedial agent cannot be highly valued, for its action is 

 only a muscle excitement or exerciser. It is a popular habit to refer all 

 phenomena, which appear too complicated for immediate understanding, to 



