Page 226 - My FlipBook

teeth, running- from forty or forty-five, as the lowest, up
to seventy or eighty, and in the one instance I found a
piece that required ninety pounds to crush the fiber of the
meat. Now, any person who has normal teeth in normal
condition ought to be able to use 125 pounds between one
upper and one lower molar tooth. This test we make with
the g-nathodynamometer. We can ascertain with this in-
strument 'how much pressure a person is able to make with
one upper and one lower tooth, or we may so place it as
to include the cusps of two teeth. Recently, particularly
in Philadelphia, there has been some question made as to
this. Some oif the older men who have been accustomed to
the thought that the dhewing of food was an easy matter,
not much force required, etc., seem to think it preposter-
ous that I and others should claim that this amount of
force can be exerted by the teeth, and question the correct-
ness of these instruments. Now, it is all right to make
a reasonable question as to the correctness of this or that
experiment, certainly, or whether the instruments made for
this or that experiment are correctly made. I will say
that these instruments are tested by the United States
weights. I haven't tested them recently, but they were
tested in the beginning and the scale markings made by
the tests. It is easy to take this apart. Put a hook upon
this spring (exhibiting), hang it up, put a tray on that and
put on the weights and test to your heart's content as to
its accuracy. Now as to accuracy, this phagodynamometer
is just about as accurate as the ordinary scales that are
made to draw from two to five hundred pounds ; it is not
accurate as to ounces; it is not positively accurate as to
half pounds, but the pounds are reasonably accurate, as
reasonably accurate as the scales in general use. This
^nathodynamometer is not quite as accurate. The condi-
tions upon which it is used make it impossible, so far, to
make this instrument quite as accurate, for this reason,
that we catch a little farther or a little less far upon vulcan-
ite pads in biting upon it ; one-third of the distance from
the end to the screw heads by which the vulcanite is at-
tached is the position in which the instrument was tested.
If we get farther toward the screw head we will not register
quite the proper number of pounds ; if we get close upon

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