1838] 



WRITINGS OF JOSEPH HENRY. 



109 



rait me to resume the subject for some months to come, I 

 therefore present them as they are ; knowing, from the in- 

 terest excited by this branch of science in every part of the 

 world, that the errors which may exist will soon be detected, 

 and the truths be further developed. 



4. The experiments are given nearly in the order in which 

 they were made; and in general they are accompanied by the 

 reflections which led to the several steps of the investigation. 

 The whole series is divided, for convenience of arrangement, 

 into six sections, although the subject may be considered as 

 consisting, principally, of two parts. The first relating to a 

 new examination of the induction of galvanic currents ; and 

 the second to the disco vexy of analogous results in the dis- 

 charge of ordinary electricity. 



5. The principal articles of apparatus used in the experi- 

 ments, consist of a number of flat coils of copper ribbon, 

 which will be designated by the names of coil No. 1, coil No. 



Fig. 1. — a represents coil No. 1, b coil No. 2, and c coil No. 3; e the 

 battery, d the rasp. 



2, &c. ; also of several coils of long wire ; and these, to dis- 

 tinguish them from the ribbons, will be called helix No. 1, 

 helix No. 2, &c. 



6. Coil No. 1 is formed of thirteen pounds of copper plate, 

 one inch and a half wide and ninety-three feet long. It is 

 well covered with two coatings of silk, and was generally 

 used in the form represented in Fig. 1, which is that of a 

 flat spiral sixteen inches in diameter. It was however some- 



