Year: 1873

play of a woodman's ak, at the distince
of a quarter of q mile, will be amused,
no matter how often it has been wit
messed, to note the difference in time
between the fall of the ax and the sound
of the blow reported to the ear. At
that distance the stroke is heard while
the AK is lifted in the air, ready for the
succeeding blow. A careful measure
ment of the velocity of sound shows that,
although it varies much with varying
circumstances, it travels usually ut the
rate of about five miles minute. This
speed is oftentimes made visible in the
flight of q cannon-ball for, although the
initial velocity of the ball is so much
greater than of sound that persons killed
within the range of mile are usually
struck before the report could be heard,
yet so greatly is its flight retarded by
atmospheric resistance that it soon
s1ackens to less than the velocity of
sound. The two rates are therefore SO
nearly alike that either may be taken as
a pretty fair representative of the other.
Should the time ever arrive-and there
is no telling what may or may not be ex-
pected-when railway speed shall equal
that of sound, then several rather queer
looking phenomena will be within the
bounds of possibility; e. g., were signal
cannon to be planted at each mile-post
along the road, and fred at the instant
of the cars passing at this rate, no report
would be heard by any of the passengers
aboard, until the train had slackened
speed at the next station, five, ten, or
twenty miles ahead, at which time all
the reports would come laundering to-
gether Again, were a cannon-bal fred
after the train, from point directly in
the rear, at the distance Of quarter of
mile, it is doubtful whether it would
overtake the train at all, unless swifter
than some cannon-balls of our day or,


if it should succeed in entering the open


back door, it would move with such
seeming laziness that passenger might
easily capture it in his hat


This brings us to consider two highly
interesting velocities in which all dwell


ers upon earth are vitality concerned, yet
to which few people have deigned more


than passing thought. The descrip


ton just now given of the maximum
rate of travel attained, and possibly at


tainable, on railways, was penned by the


writer with bated breath, for he had q


vivid recollection of the thunder and


rush of forty miles the hour over rail


road not so smooth and safe as it is now.


More than one reader, probably, will


sympathize in the feeling. Now, were


the highest rate already attained, of


sixty, eighty, or a hundred miles the


hour, increased tenfold, who would


willingly trust himself aboard any train


of cars, on any railroad built by human


hands Or who, being aboard, would


think of lying down to sleep, except I'M


der the full meaning of his childhood's s


prayer. eff I should die before
wake ?" Yet there is not mothers son


or daughter of MS Who has not been rid


ing at this tenfo1d rate all our lives, and


been going to sleep, too, every night


of our journey, as quietly and trustful-


ly as little children do within reach of q
parents arm. 1t is true. our road is


very smooth mid very safe, never having


experienced, during the last six thou


sand years, the first jolt or jar, much


less the first run-off " or collision. But


the fact that OUR so-called car is the


earth, and its great superintendent the


Almighty Creator, does not in the least


diminish the velocity with which we


travel J. nor need it diminish our won


der, though we must admit that it adds


vastly to our sense of security.


The motion of the earth has been


spoken of as if it were one only but, of


course, no one can forget that it is two


fold. In it's daily whirl upon its axis.


all who live at the equators are swept at


the rate of twenty-five thousand miles in


twenty-fcur hotifs, Or Upward of one


thousand miles an hour. Those who


live in latitude go degrees, move at ex-


actly half the speed. The average rate


at different points of the United States
may therefore be set down at about sew


en- hundred miles the hour-more than
double the velocity of sound or of a can.
: non ball


| And now what language shall we use
in speaking of that other motion of the
earth in which, we all participate We
make yearly circuit round the sun Of
about five hundred and fifty million
miles. To do this requires a veloci
ty of one million five hundred thousand


miles day, or si1tyatwU Thousand tttilet
an hour, which is upward of one thou


sand miles every minute ! This is {


speed which is actually inconceivable
Yet at this rate, as was just now said
we travel without jolt, without collision
and even without feaf of evil We si
: comfortably in our easy-going car, lool
complacently at the stars, past which w,
! so madly rush, then go to bed and sleel
l and dream, and awake in the morning
and seldom think of the grand equipag
in which we are travelling at the rate o
3 siGteera miles q second.


At this point of our survey it nigh
5 seem the dictate of reason to stop, sine
|
the conceivable. But, although pas
: that boundary, we are far from having
: reached the limits of the calcula6le
I, The electric fluid, shot along our tele
t graph-wires, SO far outstrips the dali
: molten of the sun that cable dispatc
dated London, five o'clock p. M, of an
day, is delivered in Washington Cit
e about twelve o'clock m. of the same day
s The rapidity of its transmission, thoug
!, seemingly indefinite, or, as we ordinaril
say, instantaneous, is not actually sc
Z There is an appreciable portion of tim
|. . in its transit, and that time has bee
u measured. The distance by wire be
s tween Cambridge, Massachusetts,, an
g San Francisco, California, is about thil
e ty-six hundred miles. In an experimer
e undertaken for the purpose of testin
Il its practical velocity, the electric spar
- was sent and returned over this distanc
in three-fourths of a second a rat
e sufficient to carry it round the earth
Is two seconds and half, or to comp1et
q the circuit of the earth's orbit in tw
Il hours and forty minutes, instead {
a three hundred and sixty-five days.


T, We have but one more velocity to n,
q tice. It is that of light. Until the ye,