March 30, 1882 | 
NATURE 
521 
small an-altitude. In the absence of the original observations, 
we can only conjecture that the supposed moving object or 
second comet, was none other than the Melbourne comparison 
star 8 Leporis (commonly estimated 6m.), and it may have been 
under this impression that Mr. Ellery did not think it necessary 
to reply to the telegram sent to him from Castlemaine. The 
motto of the Royal Astronomical Society, ‘‘ Qutcguid mitet 
notandum,” wpon the principle of which Dr. Bone says he acted 
in putting his observation upon record, is a good one no doubt, 
but where there is suspicion of error it is desirable to be in pos- 
session of all particulars, and in this view we would suggest the 
early publication of his comparisons as they were actually made. 
A New Comer.—A comet discovered in America, apparently 
on March 18, is likely to become a conspicuous object before 
perihelion, which, according to the first rough orbits, does not 
take place until June. 
MEDICAL ELECTRICITY 
PAPER ‘On Measurement in the Medical Application of 
Electricity,” was read before the Society of Telegraph En- 
gineers, by Dr. W. H. Stune and Dr, Walter Kilner, on March 
g. Dr. Stone commenced by stating that the subject had been 
suggested by Lieutenant-Colonel Webber, the chairman, and 
that the details the authors proposed to give that evening were 
mainly preliminary to fuller treatment, which they hoped to 
offer at some future period. 
Medical electricity, he said, had been up to now a hetero- 
geneous mixture of loose statements, doubtful diagnosis, and 
erroneous therapeutics. Glaring instances of these were given. 
With hysteria, Metallotherapy, and magnetic appliances, they 
did not propose to deal: science is in far too elementary a state 
to see through these obscure, though real phenomena. Probably, 
the key to the great enigma of the connection between electricity 
and nerve force had yet to be found. The bold statement that 
“electricity is life” is demonstrably false in: many particulars. 
Speaking generally, medical electricity had suffered from its 
exclusive handling by physiologists and physicians, who might 
receive valuable help from physicists ; indeed, the writers of the 
paper were actually soliciting such assistance at the hands of this 
young and active society. Medicine and its kindred arts lend 
themselves ill to measurement ; the tone of mind required for 
their practice is rather judicial than computative ; it is oftener 
concerned with weighing evidence, and balancing alternatives, 
than with solving equations, But men who work by measure- 
ment are usually sterling and accurate men; indeed, Prof, 
Schuster has recently shown how mathematics can help science. 
Where measurement caz be used, it should be used; and this 
was their text for the evening. 
The speaker then proceeded to divide the forms in which 
electricity had been used medically into four, namely—(1) con- 
tinuous currents, (2) continuous currents made to intermit, (3) 
induced currents, termed generally ‘‘ Faradisation,” (4) statical 
electricity. The last of these was the first employed, but it had 
given the least satisfactory results of any. The third method 
had been far the most deeply studied. Duchenne’s great work 
on Localised Electrisation early drew attention to this depart- 
ment. That genuine and indefatigable observer was able to 
point out so many definite diagnoses, and to isolate so many new 
nervous and muscular diseases by means of the induction-coil, 
that this instrument had been given somewhat excessive promi- 
nence as a therapeutic agent. Physiologists had also found in it 
a convenient stimulant for testing the action of nerves and the 
irritability of mu-cle; perhaps also the localisation of brain- 
functions. Hence muscular contraction and the action of inter- 
mittent currents iv alternate directions had been too much relied 
on as evidence of activity. One chief object of the paper was 
to point out that the future of electro-therapeutics lies more in 
the continuous current, used either in its first or second form, the 
latter of which has hitherto received little or no attention, In 
confirmation of these views, extracts were read from Prof, Erb’s 
valuable memoirs in Ziemssen’s Cyclopcedia of Medicine. 
Before, however, a single step could be taken in this scientific 
path, we must have some tolerably accurate mode of measuring 
the agent we are employing. It is obvious that the units used 
should be as far as possible those generally adopted in the 
scientific world, 
To begin with resistance : This in the human body is singu- 
larly great, and is especially located in the epidermis, which, 
zine or common salt diminishes this resistance very materially ; 
though even when care is taken in this respect, the residual op- 
position to a current is large. From hand to hand it is usually 
about 6coo ohms. In the larger bulk of the trunk, from the 
sacrum to the nape.of the neck, it never, even after long wetting, 
sinks much under 1500 ohms. That of the head, from nape to 
forehead, is about 2000 ohms. In one case it was more precisely 
1930 ohms, in an adult, and in another, a child, 2500 ohms. 
The resistance of different tissues, though not exactly to the 
present purpose, had been studicd by Prof, Eckhard, who stated 
that muscle was the best conductor, and that this being taken as 
a unit, cartilage would have a resistance twice, tendons and 
nerves about 2‘1, and bone nineteen times as great. Matteuci 
states that muscles conduct four times as well as nerves, brain, 
or spinal chord. The resistance of the skin varies from day to 
day, being modified by moisture, and by the fulness of the capil- 
lary vessels. In a particular case, the positive pole of a battery 
was placed on the sacrum of achild, and the other on the leg, 
over the extensors of the foot. By using the same current, and 
adding quickly a known resistance, the resistance of the body 
was at first found to be 11,250 ohms, which, on thoroughly 
soaking the skin, was reduced 2875 ohms, Three days previously, 
the resistance before soaking was 13,000 ohms, and after that 
process sank to 3000 ohms, Personal idiosyneracy exercises an 
influence, a delicate skin conducting better than one which is 
coarse. ‘The faceand neck offer the least ; the soles and palms 
the greatest resistance. Disease causes variation of conductivity: 
the skin over affected muscles in lead paralysis has its resistance 
increased, while in many old cases of hemiplegia it is decreased 
to a greater or less extent according to the amount of atrophy 
which has taken place. 
The resistance of muscle in disease is sometimes diminished, 
sometimes augmented. Augmentation takes place, at the com- 
mencement of degenerative changes, from the inferior conductive 
power of fat to that of healthy muscle. In a case of infantile 
paralysis, the sound leg had a resistance of 2500 ohms, the 
affected leg of 3250 ohms. Ina wasted muscle of many years’ 
standing, the enormous resistance of 16,509 ohms was reached. 
It was both easy and desirable to multiply facts such as these. 
The second preliminary point was the current which could be 
borne with impunity. Here results were very discordant. In 
the three fatal cases from touching the conductors of dynamo- 
machines, at a music-hall, in the Russian Navy, and at Hatfield, 
the necessary facts for measurement were absent; although Dr. 
Siemens had stated that he had often taken a current sufficient 
to produce a powerful light with impunity. In a case now in 
St. Thomas’s Hospital, a current of 50 milliwebers was borne 
with difficulty, and one of 20 milliwebers with ease and great 
benefit. A case of diabetes, recorded by Dr. Stone in the Pro- 
ceedings of the British Association at York in 1881, took about 
10,000 micro-ampéres, or 10 milliwebers, through his head, 
from nape to forehead, after some practice; using for its pro- 
duction from 15 to 20 cells of a bichromate battery. The parti- 
cular battery, however, mattered very little; Leclanche’s, 
bichromates and zinc-carbons with sulphate of mercury, all 
act well, and need not be of large size or small resistance. One 
was shown, in which test-tubes filled with mercuric sulphate, 
containing free acid, formed the jars ; another in which a rod of 
zinc of 5-16” diameter, and a similar sized carbon, such as is 
used in electric lamps, were immersed in the bichromate solu- 
tion. Connection was here made with the carbon by a piece of 
drawn tube sprung on to it, thus doing away with the use of 
clamps. All these, as well as most of the apparatus shown, 
were made in Dr. Stone’s workshop, chiefly with his own 
hands. 
In consequence of the high resistance of the skin, it was 
essential to give a large size to the poles employed for applying 
the current, &c. Amalgamated zinc, with the mixture of potter’s 
clay kneaded with the solution of common salt, used in physio- 
logical experiments, laid over it, was perhaps, theoretically, the 
best ; but powdered carbon placed in a bag and immersed in 
salt and water, answered equally well; or the surgical appliance 
termed Spongio-piline, a thick felt, backed by india-rubber, 
through which a well-tinned copper wire was threaded, so as to 
encompass its whole circumference without anywhere projecting 
so as to touch the cuticle. The poles could hardly be too large. 
Aconyenient form of Thomson galvanometer with graduated 
shunts, due to Dr. Kilner, was shown, and also a simple but 
effective instrument for producing intermissions in the current at 
when dry, is an excellent insulator, Wetting it wtth sulphate of any required interval of time. This apparatus consisted of a 
