Section of Medical Science. 63 
increased nearly three inches, the vessels of the skin rendered red, 
warm, and turgid, and the head relieved. 
The case of a painter was also adduced, whose right arm had long 
been paralysed and cold from the effects of lead paint. The arm 
was put for two hours into the rarefying case, and afterwards con- 
tinued hot and vigorous, so that the man was able to resume his 
work. 
Part second.—As diseases of an opposite nature require opposite 
remedies, the principle of rarefaction is reversed in certain cases, 
and condensation, or additional pressure, employed. 
This part of the paper detailed several cases illustrative of the powers 
of this agent. Where there was too much vascularity of parts, then 
local pressure, pumped under an air-tight covering, emptied the vessels, 
propelling onwards the overflow of blood contained in the veins, and 
preventing its undue influx by the arteries. 
The consequences were, to diminish inflammations, dissipate tu- 
mours and white swellings, facilitate the reduction of hernia and other 
protrusions, and to diminish the influx of fluids into indurated 
breasts or enlarged glands. 
The author adduced a very interesting case, the reduction of a 
prolapsus ani by atmospheric pressure, without touching or bruising 
the sensitive intestine. 
The powers of condensation of air were then alluded to, for the 
treatment of fungous sores or ulcers, and for the suppression of 
uterine hemorrhages, as well as bleeding from wounds or lacera- 
tions *. 
On the Differential Pulse. By Dr. WDowne tt. 
Dr. M’Donnell’s paper began with a description of what he terms 
“the Differential Pulse,” and with proofs of his claim to priority in 
ascertaining it in 1784. The observations which succeed related to 
the following subjects. 
The influence of disease and of particular remedies upon the 
pulse, with a reference to the effect of posture on the number of 
beats; the absence of this phenomenon in quadrupeds, owing to 
their natural vessels being horizontal in both the lying and standing 
posture ; certain cases of health and disease, in which the maximum 
and minimum of this variation are found ; the methods to be pursued 
for investigating the number of the pulse in wild and ferocious ani- 
mals as deducible from their respirations ; the proportion between the 
stops, pulses, and respirations in man and quadrupeds in active ex- 
ercise ; observations made at a depth of 26 feet in a diving-bell, 
which corroborate the views of Sir David Barry and Dr. Carson on 
the moving powers in the circulation; proofs that barometrical va- 
riations have no influence upon the pulse or breathings. 
Part 2.—On the limitations of the doctrine of the “ Differential 
* In vol. xiv. of the Philosophical Magazine, First Series, p. 293, was 
published a paper on Smith’s Air-Pump Vapour-Bath, an instrument which 
. was designed to effect, by the same means, many of the objects contemplated 
by Sir J. Murray.—Epir. 
