1916] on Electrical Methods in Surgical Advance 667 



receiver is attached to the surgeon's head when he is operating, and 

 one section of the wire is spring-clipped on to his knife, probe, 

 needle, or forceps, as the case may be. When the electrical circuit 

 is completed by contact between the carbon plate and the foreign 

 body, a small current is generated, which accounts for the microphonic 

 impression, and thus the surgeon is able to exercise continual control 

 ■over the foreign body. By means of a suitable relay, it would be 

 -a very simple matter, if desired, to make a sound more widely 

 audible. 



Another method of bullet extraction used by Captain A. E. Barclay 

 is worthy of mention. It combines the use of the screen with a 

 forceps, and, to replace the tactile sense of the surgeon, wires are 

 employed to lead from the prongs to a bell circuit, so that an 

 electric bell might be rung when both prongs were touching the 

 foreign body. 



Yet another device which has lately attracted a good deal of 

 attention, and is largely used in military hospitals in France, is 

 Professor Bergonie's electro-magnet. In this case a large electro- 

 magnet is excited by an alternating current and held over the 

 suspected part. If the magnetic field which is thus created embraces 

 the embedded projectile, a vibratory motion is induced in the 

 projectile, synchronizing with the pulsing of the current. The 

 surgeon palpates the part, and becomes instantly aware of any 

 vibration of the tissues which indicates the presence of the metal. 

 The point of maximum vibration having Ijeen selected, he makes an 

 incision at that point, if it is possible to do so, and then the magnet 

 is again used, and the incision deepened in accordance with the 

 information it gives. It is stated that vibration is induced, not only 

 in the ordinary magnetizable metals, but also in some of the non- 

 magnetizable, including aluminium and copper, and even, with a 

 very powerful instrument, German silver and lead. This is brought 

 about by means of induced eddy currents. 



I have attempted, all too hastily, to sketch the methods by which 

 electrical science is aiding the surgeon to repair the wounds of war, 

 but before we leave the subject we might well enlarge the view to 

 include not only the apparatus and technique, but also the men who 

 control it. The first place in our thoughts, and rightly so, is taken 

 by the combatant army, fighting so gallantly in the cause of justice 

 and freedom. It should not be forgotten, however, that behind this 

 combatant army there is another, a shadow army, following the 

 movements of the fighters as exactly as, in the experiments I have 

 shown you, the shadows on the screen followed every alteration in 

 the position of the lamp. This shadow army includes the men 

 whose fingers are always on the fine adjustments and switches, the 

 men who with infinite skill and sureness are using knife and forceps, 

 whole ranks of men engaged in a multitude of remedial tasks, from 

 the stretcher-bearer to the surgeon-general. 



