of the brain. Dr. Powell was an indefatigable student of nature,
and followed his theory through years of observation, and measured
hundreds of heads of living persons, in order to verify the correctness
of the hypothesis. His method of measuring the head may be stated as
follows: He drew a line from the occipital protuberance on the back of
the head to the junction of the frontal and malar bones, extending it to
a point above the center of the external orbit of the eye, near the
termination of the brow. Then he measured the distance between this line
and the orifice of the ear and thus obtained the measure indicating the
vital tenacity or duration of, life. Fig. 88 is a representation of the
skull of Loper, who was executed for murder in Mississippi. He might
have attained a great age, had not his violent and selfish faculties led
him into the commission of crime. In this illustration, B represents the
occipital protuberance, and A the junction of the frontal and malar
bones at the external angle of the eye. The distance between this line
(A B) and the external orifice of the ear, is the measure of the
life-force of Loper at the time of his: execution.

[Illustration: Fig. 88.]

[Illustration: Fig. 89.]

The tenacity of an individual's life, Dr. Powell determined by the
following scale of measurements: three-fourths of an inch from the
orifice of the ear to the life-line, is the average length in the adult,
and indicates _ordinary_ tenacity of life. As the distance decreases to
five-eighths, one-half, or three-eighths of an inch, vital tenacity
diminishes. If the distance is more than three-quarters of an inch, it
denotes great vital endurance, excellent recuperative powers, and is
indicative of longevity. If it measures less than half an inch, it shows
that the constitution has a feeble, uncertain hold upon life, and an
acute disease is very likely to sunder the vital relations. Dr. Powell
contended that "life force and vital force are not equivalent terms,
because much more vital force is expended upon our relations, than upon
our organization in the preservation of life. Every muscular
contraction, every thought, and every emotion requires an expenditure of
vital force." He asserted that we _inherit_ our life force or
constitutional power, and that we can determine by this _life-line,_ the
amount which we so receive. And he believed that it could be increased
by _intellectual_ effort, just as we can increase vital