Year: 1873

duced from the march ofan army, is
fairly stated at twenty miles a day,
two miles per hour, and three feet
per second. The slow pace Of the OK,
and the still slower of the tortoise and
the snail, whatsoever they may teach
of the wonders to be accomplished
by perseverance, have little the as
pect of romance. We let them pass.


The slowest motion in Nature, of
which the naked eye can take cogni-
Zance, is that of a star, as it passes
over a small moveless twig, while
the watcher rests his head against a
support. The star, we mean a fixed
star, can never be magnified by the
most powerful telescope to be more
than point of light, and we might
reasonably expect that in passing the
twig it would be suddenly and Who'll
ly quenched on one side, and as sud-
denly appear in full glory on the 9TH
er. But this is not SO its fading oc-
cupies a number of seconds, probably
because the pupil of the watchers
eve is broad enough to graduate its
light into kind of penumbra.


But there are motions in Nature
too slow to be perceived except after
q lapse of time, though we are certain
of them as we are of the march of an
arIny-the growth of a plant, for in
stance; that is, the increase of dis
tance between its root and the termin-
al bud. True, farmers tell us that
they can sometimes hear their corn
0rolU for that, in a rich bottom, af-
ter a shower, in growing weather,
the shuck will creak audibly of still
night, as its overlapping parts give
way to the increasing ear. But who
vet, unless it be whilom Jack, of
moon climbing memory, ever pro-
fessed to see the growth of any thing,
even of the most rampageous vines =?


Slow as these motions are, howev-
er, they are rapid in comparison with
others, which are familiar enough to
us all, though few persons may have
ever had the curiosity to calculate
their rate. We cut down a giant OF
the forest, and measure its parts. We
find it to be three feet in diameter,
and one hundred and fifty feet in
length, from the earth to its topmost
twig. On counting its concentric
rings, each one of which required q
year for its deposition, we learn that
il is three hundred and sixty years
old. These figures enable us to de-
termine that the growth Of the tree
upward has been at the average rate
of five inches a year-a low rase OF
velocity, truly! But what shall we
say of that other velocity, represented
by the increase of size from the cen
tire of the trunk outward ? Eighteen
inches in three hundred and sixty
years is at the rate of one-twentieth
of an inch in one year or l-73OO OF an
inch a day, or 1-1752OO OF an inch an
hour.


Slow as these rates Of motion are,
they are as truly velocities-however
they may seem rather to be tardities
as the flight Of arrows, or as the
of sunbeams, for all velocl-
ties are comparative.


Let US now exchange the micro
scope for the telescope; in other
words, turn from the lower to the
higher veloeities.


The ordinary rate Of human travel
on foot is estimated at twenty miles a
day. But men have not been content
with this snaiIs pace. They first in
creased their speed by the use OF
horsepower, which gave them an av-
erage rate of thirty or forty miles a
day. Then they devised steam pow
er, the average locomotive rate OF
which no one as yet is able to speciny.
Already the newspapers have an
nouneed IN large capitals, the as
fact-"Around rhe earth in
seventy-four days ~ feet which,
only a few years since, required ten
fold the time. Enormous, however,
as this rate of travel seems to be,
when compared in the aggregate with
former rates, it will be shorn OF much
of its apparent glory when small por-
tions of the average are compared
with other well-known rates for
twenty-five thousand miles divided
into seventy-four parts, gives the ay-
erage of not quite three hundred and
forty miles a day, or fourteen miles
per hour. This rate was not only at
tained, but even exceeded, by many
a Juvenile savage of the Pacific IS
lands. who would learn to balance
himself on the forward declivity of an
ocean billow, and ride his wild horse
shoreward until lodged upon the
sands. What is the speed Of these
pillows has probably never been esti-
mated, but those in mid-ocean have
been known to outrun the storms that
raised them, and to have attained a
velocity of forty or more miles the
hour. The rate of travel, indicated
bv the average of Round the world
in seventy-four days." is far from be-
ing the highest attained in travelling.
Forty miles per hour, equivalent to
about one thousand miles q day, Is
not uncommon, although, if any one
will look out of the car-window at the
rugged sides Of a railroad-cut, while
travelling past them az this rate, he
will be apt to feel his blood curdle at
the thought OF possible crash: Yet
even forty miles an hour is by. no
means the maximum. Twenty years
ago, express trains on some of the
best constructed English railways
were run at the fearful rate OF q mile
a minute, and, on special occasion,
when a sudden emergency demanded
it, a locomotive and its tender were
reported to have been forced up to
nearly one hundred miles an hour.


We turn from this fierce rate, so
painfully suggestive of accident, to
another which is far greater, yet gen
tie and pleasant. Any one who will


watch the play of woodman's axe
at the distance of quarter ofa mile,


will be amused, no matter how often
IT has been witnessed, to note the diff


ference in time between the fall OF
the axe and the sound Of the blow re-


ported to the ear. At that distance
the stroke is heard while the axe is
lifted in the air, ready for the sue
ceediug blow. A careful measure


ment of the velocity of sound shows
that, although it varies much with


VARYING circumstances. it travels usu-
aIly at the rate of about five miles q


minute. This speed is oftentimes
made visible in the flight Of a cannon
hall: for although the initial velocity
of the ball is so much greater than OF
sound that persons killed within the


range of q mile are usually struck be-


fore the report could be heard, yet 50


greatly is its flight retarded by atmos-


nheric resistance that 1t soon slackens
TO less than the velocity OF sound


The two rates are therefore so nearly


alike that either may be taken as q


pretty fair representative of the other.


Should the time ever arrive-and


there is no telling what may or may


not be expected-when railway speed


shall equal that of sound, then sever


al rather queer looking phenomens


will be within the bounds of possibIl'


- - efo1al oannnn IN hf