990 Transactions of the American Institute. 



V. explained also, by experiments, the variation and induction of 

 magnets. Soft iron Avill not retain magnetism, nor will iron placed 

 horizontally at right angles to the magnetic meridian retain it. 

 And upon the knowledge of this fact a very valuable discovery has 

 been made recently in England, namely, testing" axles for locomo- 

 tives, &c., by means of the needle, which detects the sllghest flaw 

 in the bars. We know little yet of the principles and properties 

 of magnetism, but we know that the earth is one vast magnet. 

 There are four metals that may be magnetized, namel}^ iron, cobalt, 

 nickel, and manganese; but it has been recently ascertained that 

 everything, except nitrogen, is magnetic, if we have instruments 

 delicate enough to test them. 



The subject was afterward discussed by Drs. Edwards, Bradley, 

 Smith, and others, who questioned Dr. Vanderweyde in regard to 

 the lines of magnetic variation of the earth, of which nothing very 

 definite is j^et known; but within the last two hundred years it has 

 shifted from east to west, and it is probable that the mass of the 

 material universe, being no doubt as highly magnetic as our earth, 

 must by their continually changing poles also influence the mag- 

 netic pole of our earth. 



HISTORY OF INDUCTION. 



Prof. Charles G. Page, of Washington, sent to the Chairman of 

 the Polytechnic his " History of the Induction Coil, and its Elec- 

 trostatic Developments," in three parts, with a request that it 

 should be laid before the Association,* The work is too voluminous 

 to be given in full. The following, mostly from Part I, embraces 

 the essential points made by the author; 



I. INDUCTION AND INDUCTION APPARATUS. 



The first galvanic or volta-electric induction appai'atus, by which 

 shocks, together with other indications of electricity of high inten- 

 sity, were obtained from a secoadary coil — that is, a coil not 

 included within the battery circuit — was made by Prof. Page. 

 This was a regularly organized apparatus of remarkable power, a 

 full description of which was communicated to SilUman^s Journal, 

 under date of JVIay 12, 1836, with the following caption: "Method 

 of increasing shocks, and experiments with Prof. Henry's apparatus 



• The letter of this distinguished inventor was written while confined to his room by ill- 

 ness, and was probably one of the last, relating to science, written by him. Professor 

 Charles Grafton Page expired on the 5th day of May, 18()8. 



