206 Dr. Faraday’s Experimental Researches in Electricity. 
amount of effect produced were the same as if the copper were 
away, and either glass or air in its place. When the dominant 
magnet was removed and the wire core made a magnet, the same 
tesults were produce 
2699. Another copper lining, being a cylinder 2:5 inches long, 
1 inch in external diameter, and one-eighth of an inch in thick- 
ness, was placed in the experimental helix, and cores of silver 
and copper five-eighths of an inch in thickness, employed as be- 
fore, with the best condition of the commutator (2675.): the ef- 
fects, with and without the copper, or with and without the glass, 
were absolutely the same (2698. ). 
2700. There can be no doubt that the copper linings, when in 
~<. place, were full of currents at the time of action, and that when 
* ‘4 away no such —— ich exist in the air or glass replacing 
“them. There is also full reason to admit, that the divergence 
“|. “éhd nibexcalieds of the magnetic lines of force supposed above 
(2697. ) would satisfactorily account for such currents in them, 
_ :+ Supposing the indirect action of the cores were assumed. If that 
_“, supposition be rejected, then it seems to me that the whole of the 
"bodies present, the magnet, the helix, the core, the copper lining, 
'__or the air or glass which replaces it, must all be in a state of ten- 
3, sion each part acting on every other part, being in what I have 
Be occasionally elsewhere imagined as the electro-tonic state (1729. ). 
wi: * 2701. The advance of the copper makes the lines of magnetic 
forée diverge, or, so.to say, drives them before it (2697. ). No 
: doubt there is a reaction upon the advancing copper, and the pro- 
« pe ion of currents in it-in such a direction as makes them com- 
a ] t, if continued, to continue the divergence. But it does not 
oye seem Wego, to say, that the currents which the lines of force 
. * cause in the per, are the, _cause of the divergence of the lines 
te? Vol force. ae 6 me, rather, that the lines of force are, 0 
| - to. eon Sagas , or bent outward by the advancing copper (or by 
«i yee a ire moving actoss lines of force in any,other form 
i 
“to the. wor 
