Faraday to Henry Bence Jones   1 December 1856¹

51A Kings Road | Brighton | 1 Decr. 1856

My dear friend

I purpose writing out an account of the little philosophic incident which interested you so much the other evening, though it is very probable that the interest may sink when the facts are plainly described. A Lady, in walking about her bedroom, ran a needle into the great toe; on searching the floor a part of a needle was found, and there was every reason to believe, from the sensation & other circumstances, that the pointed end, being broken off, was left in the toe: yet neither a friend not a surgeon could find it there[.] About two months after, and when doubts were entertained by some whether any needle was there or not, I proposed to settle that question, & if there, to say in what part of the toe it then had its place, & what was its direction[.] The following were the means employed. A fine sewing needle was well magnetized & a piece about ⅛th of an inch long was broken off. Then a filament of cocoon silk, about an inch long, had one end attached to the middle of the little magnet by a touch of soft cement, & the other end to the handle of a camel hair brush. In this way a minute test magnetic needle was obtained, which pointed well under the earths power, & could easily be brought near any part of the toe. The toe being examined by this needle, shewed occasional deflexions of the latter, which, being imperfect as indications, still seemed to imply that a piece of the broken needle was there, but rather deeply situated. Now, the means of increasing these indications and making them tell their story more perfectly was applied, and upon the following principles.- A piece of unmagnetized needle will affect a little magnet at a distance very feebly, compared to the same piece magnetized:- the unmagnetized piece will affect either end of the test needle alike, whereas the magnetized piece will affect the opposite ends in different ways, attracting one & repelling the other;- A piece of unmagnetized needle can be magnetized at a distance by a magnet of sufficient power, & as well, whilst in the toe as out of it:- also its magnetic state can be reversed if the inducing magnet be reversed, and further it can be, by management, unmagnetized, and being without magnetism is not rendered magnetic whilst the lines of force of the inducing magnet are perpendicular to it. Upon these principles I started, employing a single bar horse shoe magnet made by Logeman², with the poles so far apart that I could introduce my thumb between them. This magnet was brought up to the toe, then taken away & the part examined by the indicating needle, the indication was not stronger than before; hence one of two conclusions was probable; either there was no piece of needle there, or its position was at right angles nearly to the line joining the poles of the inducing magnet when it had been applied. So the latter magnet was employed again in a different position, & now the indicating needle told its story beautifully; shewing the little magnet which had been formed within the toe & which by its power, attracted one end of the needle & repelled the other. A few more trials with the inducing magnet shewed in what position it was able to act most strongly on the hidden needle, and then the position of the magnetic axis of the former indicated the position of the latter. Reversing the position of the inducing magnet instantly changed the magnetism of the buried needle, and now that point of the skin which before attracted the marked end of the indicating needle, repelled it strongly & attracted the other end. It was beautiful to see, when the indicating needle was carried round a given spot on the surface of the toe, how one end always pointed towards that spot; & even moved as if striving to dip down to it. Another indication, which will interest you, was afforded. The direction of the piece of needle and the locality of one end was clearly shewn; then came the question where may the other end of the piece be and what is the probable length of the whole? By carrying the indicating needle about the toe, it was found that the opposite end of the piece, though it exhibited an influence over the indicator, did not come near the opposite surface of the toe, but was buried deep in the flesh; and the piece, though manifestly piercing deep, & almost perpendicularly into the flesh, did not come near the other side. I guess it therefore to be about the third of an inch long. Presently we may tell if the needle travels and which way it is going:- all of which will be of great interest to us, who look on philosophically, and likewise to the unlucky possessor of this illustration: who I trust however will soon be able to make the experiments in her hand instead of her feet.

And now my friend here we are very comfortably situated in dry & largish rooms at 51A Kings Road - and though all tender (I am best) yet we all think it will do us good. I think if you could pop in to a cup of tea - you would approve of our locale & arrangements. Winter is very strong on the outside though perhaps he is going but we do not let him come into the house. Hoping that all with you are pretty well in which hopes as well as for those for yourself my wife & Jeannie joins me

I am | Ever truly Yours | M. Faraday

We have no occasion for a Dr. but cannot remember the name of the one you spoke of.