Year: 1874




animal Mechanics" was. the subject Of q |
lecture delivered recently in Now Haven by
Prof Trowbridge. Following are some OF it's
most interesting features: Il a' t;W Il
q Without force of friction, we would be una
bic to sit on a chair or walk the floor. With
out it, the mountains would at once become
level, and indeed all nature would cease to ex-
ist. There is spider who spins thread sol
long That it's friction in the air is 80 great that
it sustains the little animal at the end of the
thread. Ely this means he is enabled to stretch
line between points 100 feet apart The
source of power in animals is muscular con-
traction, and the possession of this power sep
arates animals from vegetables. The muscles
are composed Of large number of lunches of
extremely small threads. Each thread is con-
nected with nerve, the nerves centering in
the spinal column and thus connected with the
brain. By some means as yet undiscovered,
when the animal wishes to move muscle, the
command IS telegraphed to the brain through
the nerve to the muscle and the contraction
takes place.


The cutie fish moves by the means Of the
application of the hydrostatic press The body
of the fish is enclosed in sack. by the expan-
sion Of which it is filled with water, which en-
ters through valve SO arranged as to prevent
the water from going out. When the fish wish
rs to move, it contracts the sack and the water
is forced very powerfully out Of small tube
connected with the sack. This jet, striking
against the water of the sea, propels the fish.
The tube is generally pointed forward. and so
the fish moves backward, but if the animal
wishes to move forward, it directs the tube
backward, and it turns around with great ra-
pdity by tue same means. The larva of the
dragon Hy. has q similar contrivance for loco
motion. The principle of the hydrostatic press
ls also used by the heart in sending blood all
over the body. The progression of fish
through The water is due not to the simple lat
eral motion Of the tail but to the fact that the
tail is flexible and thus presents an inclined
plane to the water, which by its action Oh it
produces forward motion. This was llustrat-
cd by toy boat with model of fish's tail
attached to it aud operated by machinery
When placed in trough of water the boat
progressed quite rapidly to the delight of the
audience The forward motion of bird iu
fight is due to the same cause. Il ass
When a muscle is contracted and is held in
that position. the 6bres of the muscle vibrate
So times per second and this produces decom-
position of tue material of the muscle which
must be supplied by blood from the heart
When this process goes on for some time, fa-
tgue occurs. A person that becomes fatigued
by walking thirty miles would be equally fa-
tigued walkingtwice as fast when he had pas
sed over only six miles. It has been computed
that young man in boat race in an ordinary
eight oarcd oilrigger, does each minute an
amount of labor Of four foot tons, or equal to
lifting four tons one foot He exerts a power
equal to one-quarter Of horse power. where
as man ordinarily exerts but one-twentieth Of
horse power. 1t is calculated that an ordi-
nary laborer-hod-carrie or any mechanic
puts forth power represented by $50 foot-tons
per day, so that college oarsman does days
work in about an hour and twenty-seven min
utes. The labor of walking twenty-three miles
is equal to that Of climbing up ladder one
mile high The labor Of ascending three pairs
Of stairs is equal to that of walking around a
whole block 4fa4 f tA
NJ ef zsF ts


All parts of the body except the heart are
refreshed by the heart, but that organ refresh
ca itself and never rests. The tail Of one spe
cies of the shark is sconnected with the body by
ball and socket, or universal joint, by meane
Of which the tail moves through the water OBJ
liquely as an oar in sculling . boat. It is this
that enables the fish to make the enormous
leaps for which it is noted The English hunt
ing horse and the greyhound have immense
muscles on the shoulders. This is because the
fore legs have to sustain the force not only o
tue weight Of the animal but Of the great mo-
mentum acquired in their long aid rapid leaps
Afast race horse makes about 24 leaps pei
second, passing over about Is feet in that time
The lecture closed with the exhibition Of draw
lings Of the skeletons Of various animals BY
means of the stereopticon. From them we
learned, that, the rhinoceros has three toes
This animal stands on ito toes and not on The
whole foot. The elephants legs are very
l.+,r.;rht .rA honca Is caannk move fnDiiiv Il