The Waxahachie daily light. [volume] (Waxahachie, Tex.) 1894-current, 1910-08-06
THE ENERGY OF OUR JAWS.
Experiments Show Amount of Pres
sure ESerted in Eating.


Do you know that 1t is an impos-
sibility to bite the bread that moth
er makes? An absurd question, you
reply, But IL you think you can
thrust your teeth through the
particles of fluffy wheat bread you
make one of the greatest mistakes
of your life. Such is one of the
latest discoveries of science, an
nounced as a result of a series of
tests made To determine the amount
of pressure exerted by the huma}.
jaw in the process Of masticating
food.
Do you know that the woman who
participates in the ordinary CONVEX
sation of the gossipfest shuts her
jaws together with a force of siXt?
pounds every time she utters Z
syllable, while the man in vehe-
ment oratory makes teeth crash
against teeth with 100-pound blows.
DR.. Greene Vardiman Black is
the man who does know. He is the
dean Of Northwestern University'a
dental school in Chicago. For Seven
teen years he has been testing the
strength of the muscles of the hui
man jaw to ascertain how hard med
and women bite. Of late he has dl-
rected his experiments TO the num-
Der of pounds pressure eEerted by
the lower jaw IN the mastication of
different kinds of food.
The earlier experiments were
carried on by means of the gnatn5
barometer, which DR., Greene In
vented. This resembles a pair of
pliers about five inches long. The
jaws Of the device are held open by
apparatus similar to that of spring
scale, which is enclosed between
what might be termed the handles
Of the pliers. To this apparatus is
attached a pointer that registers tn.
number of pounds exerted on the
jaws of the instrument in closing OF
partly closing them. The test with
this instrument is simple. The sub
ject opens his mouth half to thres-
quarters of an inch. enough TO admit
the insertion of the jaws between
the teeth, then bites as hard as he
can on the jaws of the gnathodyna.
mometer, which are coverted with
hard rubber for the protection OF
the teeth The pointer denotes the
number of pounds pressure exertea,
Just as a pair of scales indicates the
weight of pound Of sugar at the
custom house since the government
investigation, began there.
With class of six students Prof.
Black obtained results showing
wide differences in the power of
the muscles to close the human jaws.
One student registered $50 pounds
pressure, another 1855. third 100.
the fourth 220, the fifth 225 and
the sixth $50 pounds. In tests
with other classes there were sub
jects whose maximum pressure was
as low as 100 and as high as 500
pounds. One student brought the
jaws of the gnathodynometer to-
gether with snap repeatedly. The
instrument he used. the only one
available at the time, had MAXI
mum capacity of 275 pounds. The
ease and rapidity with which he
closed 1t convinced Prof. Black
that his jaw muscles were capable
Of at least $50 pounds pressure.
All these tests and many others
OF the same kind had a specific OBJ
jeet relating to the construction OF
false teeth and the filling of natural
ones. In fact, II was In further
anee Of the scientific practice Of dem
tistry that Dir. Black investigates
the subject at all, and the same
purpose led him on 10 the study
Of the pressure OF the jaws In the
processes of masticat.on apd con-
versatior-
Bread. says Prof. Black. Is the