The Opelousas journal. [volume] (Opelousas, La.) 1868-1878, 1870-01-15
Work Performed by the Human
Heart.

That wonderful little pumping engine
which we all carry around in our bosoms,
and which runs without cessation till
death ruthlessly closes the throttle, per-
forms an amount of work so great as to
be almost beyond belief till substantiated
by arithmetical calculation.
If we scrutinze the mechanism of the
heart, we shall find that it involves in
its operations nearly all the principles
of hydrodnamics. 1t may, therefore, be
brought within the domain ofmathemat-
les as well as any other machine.
In the attempt to calculate the power
of the human heart for given tlme' we
shall arrive at some curious and interest
ing, not 70 say astonishing results. Few
would credit, at first, the statement that
the hearts now beating in and around
the city of New York, exert an aggre-
gate power ample to propel a large stea'
mer across the Atlantic ocean at fair
rate of speed, yet we shall be able to de-
monstrate that this is as much fact, as
that any of these steamers ever crossed
that storm-torn sea.
Blood is heavier than water; its spe-
cifc gravity being, according to Booth,
of from l.O527 to l.O57. For conve-
nience, however, we shall consider it
as being of the same weight as water,
extreme accuracy not being essential to
our purpose, and in our computations
We shall, for the most part and tor the
same reason, throw out fractions and use
round numbers.
The pressure required at the mouth OF
the aorta to force the blood throug h the
vessels of the human body, is estimated
by Hales as being equal per square inch
of surface, to that exerted by a column
of blood seven and one-halt feet high.
The pressure per square inch was estl-
mated by Poisenille as four pounds three
ounces. Others have estimated the pres
sure as that of q column Of water six
feet in hight. The results vary in dltfe-
rent experiments, bnt they are sufficient
ly accurate to give US an average that
we may rely upon as within bounds
| They are also something more than mere
estimates, as this pressure has been mea,
sured by pressure cages inserted into
the blood vessels.
We shall consider the pressure as that
of water column six feet in hight, the
weight of which would be nearly forty
two ounces, which, for simplicity, we
will consider forty-two ounces, or two
pounds ten ounces avoirdupois.
The average discharge of the heart at
each pulsation may be estimated at one
and one-hait ounces, and its number OF
beats at seventy five per minute: making
an aggregate of 112 ounces, or seven
pounds discharged per minute.
The average internal diameter OF the
aorta or the first great artery through
which the blood passes from the heart
into the general circulation, may be taken
as being in adults three-quarters OF an
inch
Seven pounds of blood per minute Is
therefore forced through this artery a
gainst pressure Of forty-two ounces
equivalent to raising seven pounds slz
feet each minute, equal to raising forty
two pounds one foot, or forty-two foot
, pounds.
From the diameter of the aorta ant
the amount Of blood forced through it VT
might compute the velocity of flow, bu
! that is not essential to our purpose. Al
: consideration of friction in the perform
ance of this work is also omitted, SO tha
the estimate of torty-two foot-p"unds pc
minute must be considered as considera
!, bly, less than the actual work performed
= this result corresponding to what is calle
useful aoork in the performance OF ma
chimes.
- Forty years Of this work would b
equal to the work oftwenty six thousan
seven hundred and ffty-seven horses to
> one minute of time, orr the work OF on
y horse for forty-four and one half days
:. ten hours.
u The work ofseven hundred and eighty
:. six adult hearts is equal to one-hors
power; therefore seven hundred an
!. eighty-six thousand hearts would pc
. form the work of one thousand horse
The aggregate population Of New 1orl
5 Brooklyn and Jersey City, was accort
u ing to the census of 1860, one million on
a hundred and wenty-thousand, and
u may be safely estimated now at one an
e on. half millions. Considering this
D. equal to an adult population of twel'
hundred thousand, their united hear
beats exert a power equal to that OF OF
thousand five hundred and twenty-seve
i horses. Averaging the power OF IL
y ~ united pulsations of adults and chlldre
r. - as equal to that Of four-ffths the entl
~ ~ population, and taking the census
20 1850 as basis for calculation. the wol
-, done by all the human hearts In Il
- = United States nearly equals that
~ thjrty-two thousand horses. The wol
;, done by the beating Of all the. hum;
y hearts on the globe is equivalent to II
"a power of one million forty six thousa'
~ ~ and fifteen horses. The nominal hor
~ power of the engines in the Great ia
20 % tern is four thousand; considering t
q = actual horse power to be ten thousan
;f the power exerted by the human hea
- - beat of the world is sufficient to prope
:; feet of one hundred and four Great E'
-. a. terms at full speed continually. III
- - power could only be generatedin avera
70 steam engineering practice by the co
~ bustion of four thousand six hundred a
80 81 eighty tuns of coal per hour.
" When we reflect that the human far
- y " is small in comparison even with
10 TO- great class of mammalia, of which
| IL IL