On the detection of needles and other steel instruments impacted in the human body : being part of a lecture delivered at the Aldersgate School of Medicine / by Alfred Smee.

  • Smee, Alfred, 1818-1877.
Date:
1845
Catalogue details

Licence: Public Domain Mark

Credit: On the detection of needles and other steel instruments impacted in the human body : being part of a lecture delivered at the Aldersgate School of Medicine / by Alfred Smee. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    over, that like magnetic poles repel, and opposite attract each other. You have, therefore, but to render a piece of enclosed steel a magnet, and you will be able not only to ascertain its presence, but to determine by its polarity its general direction ; and, by the amount of magnetism it evinces, you may even infer its probable bulk. When you suspect the presence of a piece of needle, or other steel instrument, you must subject the suspected part to a treat- ment calculated to render the needle magnetic; and there are two principal methods by which this object may be effected. The first, by transmitting a galvanic current, at right angles, to the suspected part; the second, by placing a large magnet near the part affected, so that the object may be magnetized by induction. You may accomplish the first end, by taking a copper wire, co- vered with cotton, or still better with silk, (in fact, you may employ the covered wire as generally used for the formation of electro-magnets,) and wind it round the parts suspected to con- tain steel, several times, so that the same current may act at right angles, many times, upon the piece of steel ; you may then take a galvanic battery (one of my little tumbler batteries will amply suflSce), and connect one end of the wire to the zinc, the other to the platinized silver. The J adjoining cut, fig. 1, will shew the ° ■ general arrangement which may be adopted to eflect this object. The current might be continued for half an hour, or more, when the steel would become magnetized, and thereby give strong indications of its presence. For my own part, I should use the second plan, or the plan of magnetizing by induction, to render the needle magnetic. For this purpose, I have employed a temporary electro-magnet, which I magnetized by the voltaic battery; and you will find, that, by keeping the part affected as close as possible to the instrument, for about half an hour, you will sufliciently obtain the desired object. The electro-magnet might be made of the horse-shoe form, if we knew the direction of the object; but, in that case, we should not require its use at all, as the proof of the existence of the needle is our only aim. I have used the horse-shoe magnet, but should prefer in most cases an electro-magnet like this, made for me by Messrs. Home, of Newgate Street, which is made of a simple straight bar of soft iron, wound round with wire. You will perceive by the adjoining diagram that the iron has a plate of brass (u) fixed on both ends to retain the wire {id) in situ ; and you may also perceive that the two ends of the wire are attached to