X-rays and localisation / by James Mackenzie Davidson.

  • Davidson, James MacKenzie.
Date:
[1902]
Catalogue details

Licence: In copyright

Credit: X-rays and localisation / by James Mackenzie Davidson. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    Eopal aittstitutian of (ir^at Britain. WEEKLY EVENING MEETING, Friday, April 25, 1902. Sib Jamks Criohton-Browke, M.D. LL,D. F.K.S., Treasurer and Vice-President, in the Chair. Jambs Mackenzie Davidson, Esq. M.B. CM. M.E.I. X-Baya and Localisation. At the end of the year 1895 Professor Eontgen announced that he had discovered a new kind of rays coming from a Orookes Tube which he called the X-rays. This discovery created a widespread interest in all parts of the world and among all classes of people, and the reason is not far to seek, because the fact that these rays have the power of passing through our bodies and casting shadows of our bones upon a photographic plate or a fluorescent screen, at once gave the discovery an intensely human interest. It is my privilege to-night to tell you something about these rays and their application in surgical practice. At the risk of being too elementary, I nevertheless purpose beginning with a short historical sketch of the scientific discoveries and developments which led up to -their discovery. - We will begin with the electric spark. Two types of instruments Se employed to produce disruptive electric discharges; the Wims- ; hurst or Holtz Influence Machine which, by merely turning a handle produces electricity at a high pressure. The other instrument is an induction coil, and it is the latter which I will use to-night in carry- ing out my experiments. The Induction coil consists of a coil of insulated thick wire bound round a bundle of soft iron wires, such as I show you here. This is called the primary. It is introduced into the interior of a large coil, consisting of a great length of very fine insulated copper wire ; this is called the secondary. In this instrument here to-night there are about nine miles of fine copper wire. The action of this instrument is based upon the discovery made in this place by that great philosopher and experimentalist, Faraday. If a current of electricity be passed through the primary coil at the moment of starting i*, there is a current induced in the secondary coil in a reverse direction; and when the current is broken in the primary, there is induced a powerful reverse current in the secondary ; so that at each make and break of the current in the primary we have two currents correspondingly induced in the secondary in opposite direc- tions, but at a much higher potential. The current induced in the secondary when the current is broken B