198 PROCEEDINGS OF THE AMERICAN ACADEMY 



Dixwell, the new series of the Academy's Transactions be pre- 

 sented to Dartmouth College. 



Four hundred and seventeenth, meeting. 



September 11, 1855. — Adjourned Quarterly Meeting. 



The President in the chair. 



Professor Joseph Henry, of the Smithsonian Institution, ad- 

 dressed the Academy on the subject of the induction of elec- 

 trical currents at great distances from the primitive current, 

 and on the oscillating movements which he had detected in 

 these currents, giving a positive or negative character at any 

 given point at different times. He also gave an account of 

 the numerous experiments he had made to establish the facts 

 which he had announced. 



Dr. A. A. Hayes remarked, that 



" The facts communicated by Professor Henry are of high in- 

 terest and importance, in their bearing on any theory of electrical 

 action. The phenomena presented in the observations of Professor 

 Henry correspond, in a remarkable manner, with those taking place 

 when a hydro-electric current acts on a conductor of the first class. 

 In the case of a continuous polarization, the central parts of such a 

 conductor exhibit no power of decomposition, even when the current 

 is feeble. A simple experiment, which illustrates this condition of a 

 polarized conductor, may be made by immersing a curved wire in a 

 solution of metallic salt, the metal of which can be displaced by the 

 metal of the curved wire. If a wire of soft bright iron, bent in the 

 form of a horseshoe magnet, have its bend barely dipped into an acid- 

 ulated solution of sulphate of copper, the copper will be deposited on 

 it as it would be on a straight wire. But if the curved wire be lowered 

 into the solution, or if at first it be at once immersed, the deposition 

 of copper by displacement occurs at the free extremities of the wire 

 and extends towards the bend from them. It ceases, however, before 

 it reaches the bend, or central part, which never receives more than 

 the slight coating due to the instant exposure in immersing it. This 

 experiment may be varied by modified curves of the wire ; but how- 

 ever numerous the forms of the bends, the central part of each wire 

 or plate is null in its action as an electrode." 



