

191 Prof. A. M. Mayer on the Magnetic Elongations 



The following experiments were made on rod No. 3, of English 

 refined iron ; and each result is the mean of fifty experiments. 

 Time of elongation. Time of retraction. 



(1) 25 cells. . . go °f a secon d. i% °f a secoa d. 



(2) lcell. . . ft „ A „ 



It is thus seen that with twenty-five cells the duration of re- 

 traction is six times as long as the duration of the elongation ; 

 but with a current from one cell the phenomena are reversed, and 

 the duration of the elongation is three times that of the retraction. 



Determinations of the times occupied in the elongation and the retrac- 

 tion of a rod when the inner or the outer helix forms in itself a 

 closed circuit, while the current is passed in the respective 

 cases in the outer and in the inner helix. 



(1) Terminals of inner helix not joined. Current passed 

 through the outer helix from twenty-five cells. Elongation of 

 the rod 1'5 division. Time of elongation t Jq of a second. 

 Time of retraction J of a second. 



(2) Same results as above when the outer helix was open and 

 the current was passed through the inner helix. 



(3) The terminals of inner helix united, so that this helix 

 formed a closed circuit in itself. Current from twenty-five cells 

 passed through outer helix. Elongation 1*5 division. 



Time of elongation -— of a second. Time of retraction 

 1-jL of a second. 



(4) Same results as above when the terminals of the outer 

 helix were united and the current passed through the inner 

 helix. 



(5) One cell used. When the terminals of outer or inner 

 helix were not united, and the current passed respectively 

 through inner or outer helix, the elongation was 1*1 division, 

 the time of elongation T 3 o of a second, the time of retraction T 3 o 

 of a second. 



(6) One cell used. The terminals of inner helix united. The 

 elongation was 1*1 division. Time of elongation T ^,j of a 

 second. Time of retraction l^j of a second. 



(7) Same results as experiment (6) when the terminals of 

 outer helix were joined and the current from one cell passed 

 through the inner helix. 



To observe a rod slowly retracting during 1*3 of a second was 

 a most remarkable sight, and suggests many thoughts as to the 

 interaction of the induced currents passing in the helices and 

 rod. I may here venture to suggest that the study of these ex- 

 traordinary phenomena (which I believe I have here first made 

 known) will eventually be of some service in the investigation of 



