294 



NATURE 



[June i, 191 6 



north of France, Belgium, and South Wales were illus- 

 trated by a map. It was shown that the line of 

 intense disturbance on which the Continental coal- 

 fields were situated was more likely to pass south of 

 the Kent coal-field than through it, and that the 

 coal-field occupied a position comparable in this respect 

 to that of the newly discovered coal-field of La Cam- 

 pine. Whether the disturbed belt was continuous 

 under the south of England and joined up with the 

 Armorican folding of South Wales and Somerset could 

 be proved by further borings, and in no other way. 



The registration and correct interpretation of borings 

 were matters of great importance. A recommendation 

 made by the Royal Commission on Coal Supplies, that 

 particulars should be collected and preserved in a 

 Government office, had not led to any action. As 

 matters now stood, the records were not only liable 

 to be lost or grossly misinterpreted, but some had 

 gone so far astray as to be accessible only in a German 

 publication. 



ELECTRICAL METHODS IN SURGICAL 

 ADVANCED 



NO institution in the world (said Sir James Mac- 

 kenzie Davidson) had contributed so largely to 

 electrical science as the Royal Institution of Great 

 Britain. All modern electrical developments were 

 based to a greater or less extent upon the work of 

 Michael Faraday and his master, Sir Humphry Davy ; 

 and it was fitting, therefore, that in the place which 

 would always be associated with their labours some 

 account should be given of those same electrical 

 developments as applied in the present day to the art 

 of the surgeon. 



Before electricity came on the scene the examina- 

 tion of wounded men who had bullets lodged in their 

 .tissues was largely dependent on guesswork. As an 

 early instance of the tentative application of more 

 scientific methods, he mentioned the case of Gari- 

 baldi, who, after the battle of Aspromonte, was 

 troubled by a wound in the ankle which refused to 

 heal. The presence of an impacted bullet in the foot 

 was not detected until N^laton, with a whalebone 

 probe having at the end a button of porcelain, 

 managed by introducing it into the wound to make a 

 rubbing contact with whatever it was touching, and 

 found on the tip a black mark caused by the embedded 

 lead. 



Such a method in these days would not carry us 

 very far, but since then the discovery of X-rays had 

 come along to revolutionise surgical diagnosis. Sir 

 James gave a description of the production of X-rays 

 with the most modern of tubes — the Coolidge — and 

 then went on to point out that although the shadow 

 picture produced by X-rays gave a good deal of in- 

 formation as to the relative densities of any interposed 

 materials, it was not like an ordinarv photograph 

 from which the relative positions of objects could be 

 inferred. It was a shadow of the object, and there- 

 fore might be very misleading. He showed on the 

 screen two X-ray pictures of exactly the same sub- 

 ject, in which, however, the tube had occupied slightly 

 different positions. In the one case a bullet appeared 

 to be in the right lung, and in the other in the left. 

 Something more was needed than the single X-rav 

 photograph if any correct information as to the posi- 

 tion of a foreign bodv was to be obtained. 



There was. first, the stereoscopic method, and this 

 he illustrated by having two little electric bulbs side 

 by side, one of them surrounded by a green film of 

 gelatine, and the other by a red film, each casting a 

 shadow of an object — a cone of wire — from slightly 



1 Abstract of arfiscourse delivered at the Royal Institution on May 5, by 

 Sir James Mackenzie Davidson. 



NO. 2431, VOL. 97] 



different points of view. Spectacles consisting of red 

 and of green lenses were distributed among the audi- 

 ence, and when the shadows were viewed through 

 these they combined to give an impression of solidity, 

 as though the actual object were being looked at 

 instead of its shadow. With the spectacles reversed, 

 the effect became a pseudo-stereoscopic one. 



This was not precise enough, however, for the 

 purpose of exact localisation, and in order to arrive 

 at mathematical accuracy a different system was 

 available. Here the lecturer gave a description of his 

 own well-known cross-thread localising method, and 

 the manner in which the geometrical conditions under 

 which the two X-ray pictures were produced are re- 

 constructed so as to interpret the various findings on 

 the negative in the terms of exact measurements 

 which the surgeon required to employ. It was really 

 the method of similar triangles. If more rapid pro- 

 cedures were demanded, as they might well be by the 

 exigencies of the present time, the same measurements 

 could be carried out with a hand lluoroscope (shown) 

 and a device consisting of scale, cross wires, and slid- 

 ing piece, calibrated sq as to enable one to determine 

 by the simplest adjustment the depth of a piece of 

 metal below a marked point on the skin by noting the 

 displacement of the shadow on the illuminated screen 

 when the tube was moved to a given distance. 



Having ascertained the position of the bullet, other 

 electrical aids were available for the surgeon when he 

 came to deal with its extraction. One of the most 

 useful was the telephone attachment, consisting of a 

 telephone to one terminal of which was attached the 

 surgeon's exploring instrument, and to the other a 

 carbon plate which, moistened with salt water, was 

 applied to the patient's skin. When the exploring in- 

 strument came into contact with embedded metals, a 

 loud click was elicited, .becoming a sharp rattle on a 

 rubbing contact. A small current, generated when the 

 electrical circuit was completed by contact between the 

 carbon plate and the foreign body, accounted for the 

 microphonic impression. Through the kindness of 

 Mr. Campbell Swinton, who had installed a special 

 loud telephone, the rattling sound, usually heard only 

 by the surgeon when the receiver was close to his 

 ear, was audible all over the theatre. The lecturer 

 also showed the ingenious telephone forceps with 

 X-ray screen attached, adapted by Captain A. E. 

 Barclay, of Manchester. 



Another device for the same purpose, largely used 

 in France, was Prof. Bergoni6's electromagnet, of 

 which, through the kindness of Dr. Ettie Sayer, the 

 lecturer was able to show an example. In this case 

 a large electromagnet was excited by an alternating 

 current and held over the suspected part. If the mag- 

 netic field thus created • embraced the embedded pro- 

 jectile, a vibratory motion was induced in the latter, 

 synchronising with the pulsing of the current. The 

 surgeon palpated the part and became instantly aware 

 of any vibration of the tissues which indicated the 

 presence of the metal. The point of maximum vibra- 

 tion having been selected, he made an incision at that 

 point, and then the magnet was again used and 

 the incision deepened in accordance with the informa- 

 tion it gave. The lecturer was able to repeat this 

 action on a smaller scale with some pieces of high- 

 explosive shell (lent to him by Dr. Menzies) placed in 

 gelatine, and their vibrations when brought within the 

 influence of the magnet were projected on the screen. 



The lecturer concluded with a tribute to what he 

 called the shadow-army (consisting of workers in all 

 branches of war surgery), who followed the move- 

 ments of the combatant army as exactlv as in the 

 experiments he had shown them the shadows on the 

 screen followed every alteration in the position of the 

 lamp. 



