DISCOURSE OF W. B. TAYLOR. 249 



necting the secondary coil with another at some distance from the 

 primary so as not to be influenced by it directly, but forming with 

 the secondary a single closed circuit, not only was the distant coil 

 capable of producing in an insulated wire helix placed over it, a 

 distinct current of induction at the interruption of the primary, 

 but sensible shocks were obtained from it. The experiment was 

 pushed still further; and inductive currents of a fourth degree 

 were obtained. "By a similar but more extended arrangement, 

 shocks were received from currents of a fourth and a fifth order: 

 and with a more powerful primary current, and additional coils, a 

 still greater number of successive inductions might be obtained. 

 - - - It was found that with the small battery a shock could 

 be given from the current of the third order to twenty-five persons 

 joining hands; also shocks perceptible in the arms were obtained 

 from a current of the fifth order." As Henry simply remarks: 

 "The induction of currents of different orders, of sufficient inten- 

 sity to give shocks, could scarcely have been anticipated from our 

 previous knowledge of the subject." By means of the small 

 magnetizing helix introduced into each circuit, the direction of 

 these successive currents was found to be alternating or reversed to 

 each other. These remarkable results were obtained in the summer 

 of 1838.* 



The concluding section of this important memoir is occupied 

 with an account of " The production of induced currents of the 

 different orders, from ordinary electricity." An open glass cylinder 

 about six inches in diameter was provided with two long narrow 

 strips of tin foil pasted around it in corresponding helical courses, 

 the one on the outside and the other on the inside, directly opposite 

 to each other. The inner coiled strip had its extremities connected 

 with insulated wires which formed a circuit outside the cylinder, 

 and included a small magnetizing helix. The outer tin foil strip 

 was also connected with wires so that an electrical discharge from a 

 half-gallon Leyden jar could be passed through it. The magneti- 

 zation of a small needle indicated an induced current through the 

 inner tin-foil ribbon corresponding in direction with the outer cur- 



* Trans. Am. Phil. Soc. vol. vi. (n. s.) p. 303. 



