Year: 1874

Ina recent number the Journal Of Chem
istJy explained how "a days work Is
measured in fOOt-tOnS, and its average
amount, including both the "eXternal
work. or that performed in labor or walk
ING, and the internal work, or that
done by the organs of circulation, reSpira-
tion, digestion and other vital processes.
The former averages from 800 to 500 foot
tons. the higher figure representing an eX-
ceedingly hard days work. The latter
may be reckOned taking the average of
the best estimates, at 2G0 iOot-tons. As
might be expected, it is difficult to measure
this internal work with precision, and the
estimates of different psychologists vary
widely. those for the heart alone ranging
from l22 to 277 fOOt-tOns. The former is
the amount calculated by HaughtOn, who
puts the respiratory movements at about
IL foOt-tOns for the 81 hours, while others
have set them as high as A foOt-tOns.
The exact value is of no importance for
our present purpose. Taking the lowest
estimate, the internal work is no insigniti-
cant addition 20 the other labor performed
by the wonderful mechanism of this body
of ours.


Where does all this force come from?
What keeps the machine going2 The idea
of perpetual notion" or a selfmOving
machine, is as absurd here as in any other
department of mechanics. A steam-en-
CINE may as well be expected to run with
Out its boiler and furnace, as the body
without its equivalent for boiler and fur
mace and both alike must have fuel to
keep UP their fires. We need not dwell
on this point, for the fact that the food
we eat maintains the heat of the
body. builds up and renews its mus
FfZhn oil r.
varied energies, has been familiarity eX-
planned. 1t has been shown, moreover,
that the food is literally burned to produce
this heat and force, and that the air we
breathe supports this combustion, which
is process OF oxidation, and dependent
on a constant supply of oxygen, precisely
like the fire under the boiler of the steam
engine.


Now, we know that it is impossible to
calculate Just how much work a pound o
coal burned in the furnace of an engine is
capable of doing. The heat generated in
the combustion is equivalent to something
more than 100000 foot pounds, and if
none of it were wasted it would actually
do that amount of work. In the steam
engine, however, only about a tenth part
Of the energy stored up in the fuel is real
lied as work.


MAY we UOJ CdlCuldtC III luc Sdult NdJ
what work the food we eat, considered as
fuel is capable of doing, and compare this
result with the actual amount accomplish
ed by il in the body? The problem is
somewhat more complicated than in the
case of the the steam-engine, but several
Psychologists have tried their hand at it,
and have attained reasonably consistent
results.


Dr. FTankland has determined the me-
chanical energy Of various kinds of food,
both when burnt in oxygen and when
consumed in the body. The amount is
sometimes smaller in the latter case than in
the former, because the combustion is not
so complete. For example, an ounce OF
albumen generates certain amount of
heat when burnt in oxygen; but in the
body some of its constituents are only par
TALLY OxidiZed, being eXcreted in the form
of urea. An ounce of sugar, Oh the other
hand, is generally all burnt up into car
bOnic acid and water, and its actual en-
ergy in the body, under whatever form
it appears, is equivalent to its theoretical
energy,