A reproduction of some portions of Faraday's diary : presented by the managers of the Royal Institution of Great Britain / [Michael Faraday].

  • Faraday, Michael, 1791-1867.
Date:
[1931]
Catalogue details

Licence: In copyright

Credit: A reproduction of some portions of Faraday's diary : presented by the managers of the Royal Institution of Great Britain / [Michael Faraday]. Source: Wellcome Collection.

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    8. Hence effect evident but transient; but its recurrence on breaking the connection shews an equilibrium somewhere that must be capable of being rendered more distinct. 9. The direction of the pole towards the helix was, when the contact was first made, as if the helix round B was a part of that at A, i.e. the electric currents in both were in the same direction; but when the contact with the battery was broken the motion of the needle was as if a current in the opposite direction existed for a moment. 10. Had a short cylinder of iron | thick, 4 inches long, and coiled round with 4 pieces of wire each about 14 feet long: made these coils into one and substituted this in place of the flat helix. The needle was affected as before, but not at all as if the iron had helped to develope magnetic power—not more than helices round it would probably have done without the iron. It was the same transient and inverted states as before. 11. Removed the iron and helices and substituted two platina poles to ends of B coil; put these into solution of copper, lead, etc. etc., but could get no evidence of chemical action. Put solution of copper on to one pole and then touched the drop with the other; then connected the battery, then broke connection at drop, and then at battery, and so went on in succession so as to avoid the recurrence of the return or opposite current on the drop: but got no evidence of chemical action. 12. On making all the wire round the iron ring one helix and sending current from battery through it, and also hanging a magnetic needle over the ring, one pole being in the middle at the point of suspension, the needle darted about irregularly and shewed poles—two N and two S. On putting paper over the ring and sprinkling filings over it also see the 4 poles, but were ir¬ regularly placed. Iron probably not soft but evidently not a per¬ fect conductor, for the parts between the ends of the two general helices of A and B were of very different magnetic power to the ends of the helices. 13. Put a helix (of brass brace spring) round a glass jar and brought a needle within it in various positions, but it behaved merely as a single ring of wire would have done.