170 Miscellanies. 



Again, for the longitude of Brown University, Providence, Mr. 



Paine finds, 



m. s. 

 Boston — Providence, 1 22.64 by 40 chronometers. 



do. 1 22.29 by eclipse of May 15th, 1836. 



Mr. Paine's observations of the eclipse of Sept. 18th have already 

 been reported. Those for latitude and regulation of chronometers 

 have been stated more at length, in order to furnish examples of the 

 method pursued by that gentleman in the chronometric survey of 

 Massachusetts, the only work of the kind of much extent hitherto 

 performed in this country. Some idea of the labors of Mr. Paine 

 may be formed from the fact, that, during its progress, he has been 

 under the necessity of making and reducing more than 100,000 ob- 

 servations of altitudes of the sun and stars, without any assistance. 



It is proper to add that Mr. Gilliss's observations, already reported, 

 appear to require a subtractive correction of 1.955. Thus Mr. Paine's 

 observations give, 



h. m. in. s. 



Sept. 18th, 21 25, Barraud 151, fast by its own rate, +19 

 by comparison with 682 Barraud, 

 1678 Arnold, 

 by mean of three chronometers, 

 by Mr. Gilliss's transit observations, 

 Discrepancy, 



Professor Henry read a paper entitled " Contributions to Electri- 

 city and Magnetism, No. 3. On the Phenomena of Electro-dynamic 

 Induction." Referred to Prof. A. D. Bache, Dr. Patterson, and Dr. 

 Hare. 



The primary object of the investigation undertaken by the author, 

 was the discovery of induced currents from ordinary electricity, sim- 

 ilar to those produced by galvanism. Preparatory to this, a new 

 investigation was instituted of the phenomena of galvanic induction, 

 and the result of this forms, perhaps, the most important part of the 

 communication. 



The first section of the paper refers to the conditions which influ- 

 ence the induction of a current on itself, as in the case of a long 

 wire and a spiral conductor. These are shown to ^depend on the 

 intensity and quantity of the battery current, and on the length, thick- 

 ness, and form of the conductor. 



The next section examines the conditions necessary to the produc- 

 tion of powerful secondary cui*rents, and also the changes which take 

 place in the same, when the form of the battery, and the size and form 

 of the conductor are varied. The important fact is shown, that not 

 only a current of intensity can be induced by one of quantity, but 



