92 NATURE 
[Marcu 25, 1915 

for our knowledge of which we are mainly 
indebted to the author’s powers of observation. 
These powers are so rarely at fault that it seems 
almost ungracious to indicate the only instance in 
which he appears to have been led into misappre- 
hension; there is one passage in which what, 
from his succinct description, was obviously a 
silk-cotton tree has been confused with that— 
from a phytogeographical point of view—extremely 
interesting species, the tulip-tree of China. The 
book is admirably printed, and in its 600 or so 
pages we have noticed but one typographical 
error. 

THE TELEPHONE IN SURGERY. 
ey the Lancet of January 30 is published an 
address by Sir James Mackenzie Davidson, 
delivered before the Medical Society of London, 
on the telephone attachment in surgery. By this 
phrase the author refers to the attachment of a 
telephone receiver to a probe, or lancet, or other 
metallic instrument used by a surgeon when ex- 
ploring a wound containing a bullet or other piece 
of extraneous metallic matter, in such a way that 
the sound heard in the telephone when the probe 
comes into contact with the bullet enables the 
surgeon to make certain of the position of the 
bullet in the wound. 
As this matter appears to be of real importance 
at the moment to surgeons in the field hospitals 
of our armies abroad, we make no apologies for 
giving our readers a summary of the more salient 
features of Sir Mackenzie Davidson’s address. 
His attention was first directed to the use of the 
telephone as an auxiliary in surgery thirty-two 
years ago, by the accounts of the attempts made 
by Graham Bell, to determine, by means of the 
induction balance, the position of the bullet in the 
body of President Garfield when he was assassin- 
ated in 1881. Speaking afterwards of these 
attempts, and of the difficulties attending the 
method—which had failed in that notable case to 
yield satisfactory indications—Graham Bell out- 
lined another and simpler electrical method for the 
detection of bullets, as follows :— 
It consists of a telephone, to one terminal of which 
a fine needle is fixed, and to the other a plate of metal 
of the same nature as the needle. The plate is placed 
on the limb to be examined, and the needle is thrust 
in where the bullet is believed to be; and when it 
strikes the ball a galvanic battery is formed within 
the body. . . . This will cause a click to be heard in 
the telephone each time the bullet is struck. This is a 
far simpler apparatus than the induction balance, and 
one far more easily procured. 
This method Sir Mackenzie Davidson tried in 
1887 at the Aberdeen Royal Infirmary, in the case 
of a patient suffering from a revolver shot, using 
a silver probe joined by a wire to one terminal, 
and a silver plate, about 6 inches long and 4 inches 
wide, connected by wire to the other terminal of 
a telephone receiver. In subsequent years he 
employed the same method to verify the results of 
early X-ray localisations, and it enabled surgeons 
in the South African War to differentiate, as the 
NG. 2369, VOL. 95| 



common probe could not do, between a distorted 
and broken up Mauser bullet and a fragment of 
bone. Sir Mackenzie Davidson states that until 
quite recently he took it for granted that the same 
metal must be used—as Graham Bell stated—for 
the probing instrument and for the plate placed 
upon the patient’s skin. But since the outbreak 
of the present war the difficulty experienced by 
skilful surgeons in finding bullets in wounds, even 
after the most precise localisation by means of 
X-rays, has caused him to experiment further, 
and to extend the method. Briefly, he 
finds, as the result of experimenting on different 
pairs of metals, that there is nothing so satis- 
factory as a plate of carbon, such as is used in 
an ordinary bichromate cell, to place upon the 
moistened skin of the patient as the auxiliary pole. 
The surgeon’s metallic instruments are usually of 
steel, often silver-plated or nickel-plated. The 
metals to be sought for are lead, iron (and iron 
alloys), copper, and nickel. Carbon presents a 
sufficiently wide difference in its galvanic proper- 
ties from any of these to render it suitable. The 
result is enhanced if the solution used to moisten 
the skin beneath the plate is the solution of iodine 
employed as a disinfecting agent, since iodine is 
also an excellent depolariser. A low-resistance 
telephone is better adapted than the more ex- 
pensive high-resistance receivers used in wireless 
telegraphy, giving louder sounds besides being 
cheaper. 
The form of telephone recommended is one with 
double receivers fixed to a flexible steel hoop that 
is placed on the head, so that each ear listens to 
its own receiver, and is protected from extraneous 
sounds. The operating surgeon places the 
auxiliary carbon plate upon the patient’s moistened 
skin at some convenient spot near the place where 
the foreign object is supposed to be situated, and 
it may be held tightly against the skin by bandage 
or plaster. If a bare wire of silver is used as 
probe, it should, of course, be properly disin- 
fected. Or the wire may be wound round an 
ordinary probe or needle or forceps which is used, 
or a spring clip may be employed to connect the 
instrument to the wire connected to the telephone. 
No battery of any kind is needed, owing to the 
galvanic action between the carbon-plate and the 
metal of the bullet. If, under these conditions, 
the instrument is introduced into the body of the 
patient, it will on the first contact with the bullet 
or other metallic body cause a most unmistakable 
click ; while if the probe or scalpel is gently moved 
along the foreign body so as to make rubbing 
contact along it, an equally unmistakable rattling 
sound will be heard. Several examples _ of 
successful application, showing the advantages 
gained by the use of this method, are given by 
Sir Mackenzie, who states it to be his belief “that 
the time will come when no surgeon will attempt 
to remove a deeply embedded metallic body 
without having this telephone attachment at his 
command.” He makes out an exceedingly good 
case for this application of the telephone to 
surgery. 
