they are felt
as two. Obtuseness varies with the type of crime committed habitually by
the subject; in burglars, swindlers, and assaulters, being approximately
double, while in violators, murderers, and incendiaries it stands in the
ratio of 5 to 1 compared with normal persons.

In the absence of an esthesiometer, a rough calculation may be made by
using an ordinary drawing compass or even a hairpin, separating the two
points and measuring with the eye the distance at which they are felt to
be separate.

_General Sensibility and Sensibility to Pain_ are measured by a common
electric apparatus (Du Bois-Reymond), adapted by Lombroso for use as an
algometer. (See Fig. 35.) It consists of an induction coil, put into
action by a bichromate battery. The poles of the secondary coil are
placed in contact with the back of the patient's hand and brought slowly
up behind the index finger, when the strength of the induced current is
increased until the patient feels a prickling sensation in the skin
(general sensibility) and subsequently a sharp pain (sensibility to
pain). The general sensibility of normal individuals is 40 and the
sensibility to pain, 10-25: the sensibility of the criminal is much less
acute and sometimes non-existent.

_Sensibility to Pressure._ Various metal cubes of equal size but
different weight, are placed two by two, one on each side, on different
parts of the back of the hand. The patient is then asked to state which
of any two weights is the lighter or heavier. This sense is fairly acute
in criminals.

_Sensibility to Heat._ Experiments are made by placing on the skin of
the patient various receptacles filled with water at different
temperatures. If great exactitude is desirable, Nothnagel's
thermo-esthesiometer should be used. This is an instrument very similar
to Weber's esthesiometer, but the points are replaced by receptacles
filled with water of varying heat and furnished with thermometers. The
patient must state which is the colder, and which the hotter spot.
Sensibility to heat is less acute in criminals than in normal
individuals.

_Localisation of Sensibility._ After the patient has been requested to
close his eyes, various parts of his body are touched with the finger
and he is asked to point out the exact spot touched. Should he not be
able to reach it with his finger, a statuette should be placed before
him on which he should mark with a pencil the part touched. Normal
persons are alwa