140 WRITINGS OF JOSEPH HENRY. [1838 



wires was increased to sixteen inches, and the ends of the 

 second wire placed in two glasses of mercury, and a finger of 

 each hand plunged into the metal, a shock was received. 

 The direction of the current was still the same, but the mag- 

 netism not as strong as at a less distance. 



122. The second wire was next arranged around the other, 

 so as to enclose it. The magnetism by this arrangement ap- 

 peared stronger than with the last ; the direction of the cur- 

 rent was still the same, and continued thus, until the two 

 wires were at every point separated to the distance of twelve 

 feet, except in one place where they were obliged to be 

 crossed at the distance of seven feet, but here the wires were 

 made to form a right angle with each other, and the effect 

 of the approximation was therefore (46) considered as noth- 

 ing. The needle at this surprising distance was tolerably 

 strongly magnetized, as was shown by the quantity of filings 

 which would adhere to it. The direction of the current was 

 still the same as that of the battery. The form of the room 

 did not permit the two wires to be separated to a greater dis- 

 tance. The whole length of the circuit of the interior large 

 wire was about eighty feet ; that of the exterior one hun- 

 dred and twenty. The two were not in the same plane, and 

 a part of the outer passed through a small adjoining room. 



123; The results exhibited in this experiment are such as 

 could scarcely have been anticipated by our previous knowl- 

 edge of the electrical discharge. They evince a remarkable 

 inductive energy, which has not before been distinctly recog- 

 nized, but which must perform an important part in the dis- 

 charge of electricity from the clouds. Some effects which 

 have been observed during thunder storms, appear to be due 

 to an action of this kind. 



124. Since a discharge of ordinary electricity produces a 

 secondary current in an adjoining wire, it should also 

 produce an analogous effect in its own wire; and to this 

 cause may be now referred the peculiar action of a long con- 

 ductor. It is well known that the spark from a very long 

 wire, although quite short, is remarkably pungent. I was 

 60 fortunate as to witness a very interesting exhibition of 



