Knoxville journal. [volume] (Knoxville, Iowa) 1874-1986, 1875-11-18

DR.. Du Chaumont in a recen, lec4,,.
said that up to quite late date there y.s
an absence of any satisfactory theory as -
the relation of food to work, and II We.
supposed that bodily force was due 10 :
chemical change in the muscles them.
selves, and that heterogeneous matter !,
food repaired the waste. But the ra-
searches OF Joule, Playfair, Frankland
and others On the conservation of enervv
have led to the conclusion that acttys
force is produced chiefly by the potential
energy stored up in the carboniferous
food and set free by oxidation. Hence Il
was seen that to credit the chemical
changes in the muscles with the origina.
ton of force in the body was not more
philosophical than TO credit the force ex.
erted by u steam-engine to the wearing
away Of Its wheels and pistons.
The lecturer then proceeded through a
large number of elaborate calculations
based upon actual observation, for the
purpose of showing the ordinary amount
of productive work of which man of
average height is capable, and its equiva.
lent in foot rons-a foot ton Representing
the amount of force required to raise one
ton one foot high. 1t appears that the
work done in walking three miles an
hour is equal to about one-tenth the work
done by direct ascent. Three hundred
foot tons is fair days work for man of
average height This would be equiva-
lent to walking fifteen miles in little
over five hours. A hard days work
would be equivalent to walking twenty
four miles in eight hours. DR.. Parkes
mentions an extreme case in which man
in copper mill did as much as 723 foot
tons in day, his average work being
443 foot tons. The ordinary work OF
a military prisoner IL 80 foot tons
The velocity at which work was done
and the consequent resistance, greatly az
feet the quantity Of potential energy re.
quired for its accomplishment. For the
production of any amount Of what may be
termed productive work much larger
amount Of potential energy has to be ex-
pended. Prof. Haughton, of Dublin, has
calculated that, Of the total potential
energy produced in the body, 2G0 fost
tons are required for the action Of the
heart Then the animal heat absorbs from
1900 to 1850 foot tons, or more.
According to Helmholtz. about five
times as much energy is used in the inter
nal work of the body as is expended in
ordinary productive work. In the case Of
severe work the proportion of internal
work to productive work is still greater
Surprising the work performed by man
to consist of walking, the most economical
rate, both as regards the amount of food
required to sustain il and the amount of
potential energy expended on the body
itself, is about three miles an hour. Both
above and below that speed there is a de-
crease In the amount of active work as
compared with the non productive energy.
A man walking fifteen or sixteen miles a
day, or doing an equivalent amount OF
work in another form, would require %
ozs Of food, composed of aibuminates as
ozs., fat 3 ozs., starch 14.3 or, and salts
IL ozs. This would yield potential
energy of A ,430 foot tons, and 300 foot
tons for productive work. A mere sub
sistcnce diet for man at rest would be Is
ozs., but with this amount man would
lose weight. About 1000 foot tons day
of potential energy is about the greatest
amount which IL possible as a pcrmanency.
This would yield 600 foot tons of produc-
tive work. These calculations apply only
to men in health. --Scte,.tttic american.