Watertown republican. [volume] (Watertown, Wis.) 1860-1906, 1873-05-28
COMPARATIVE VEIOCITIES.
BY F. R. GOULDING.


ed at twenty miles 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 ac-
complished by perseverance, have little
the aspect of romance. We let them
pass.
The slowest motion in Nature, of which
the naked eye can take cognizance, is that
of star as it passes over a small move
less twig, while the watcher rests his head
against support The star, we mean
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 wholly quenched on one
side, and as suddenly appear in full glory
on the other. But this is not so; its fad
ing occupies number of seconds, proba-
bly, because the pupil of the watchers eye
is broad enough to graduate it's light into
a kind of penumbra.
But there are motions in Nature too
slow to be perceived except after lapse
OF time, though we are certain of them as
we are Of the march of an army-the
growth OF plant, for instance; that is,
the increase Of distance between it's root
and the terminal bud True, farmers tell
us that they can sometimes hear their corn
gr0ao; for that, in rich bottom, after
shower, in growing weather, the shuck
will creak audibly of a still night, as it's
overlapping parts give way to the increas-
ing ear. But who yet unless it be whilom
Jack, of moon-climbing memory, ever
protested to see the growth Of any thing,
even of the most rampageous vines?
Slow as these motions are, however,
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 meas
ure its parts. We find it to be three feet
in diameter, and one hundred and fifty
feet in length, from the earth to its top
most twig. On counting its concentric
rings each one of which required a year
for its deposition, we learn that it is three
hundred and sixty years old These fig
ures enable us to determine that the
growth of the tree upward has been at the
average rate of five inches year-a low
rate of velocity, truly! But what shall we
say of that other velocity, represented by
the increase of size from the centre of the
trunk outward? Eighteen inches in three
hundred and sixty years is at the rate OF
onetwentieth of an inch in one year or
7so OF an inch day, or -z=za77 of an inch
an hour.
Slow as these rates of motion are they
are as truly velocit1es however they NAV
seem rather to be tardlt5es-as the flight
of arrows, or as the flashing Of sunbeams,
for all velocitics are comparative.
LET lis now pYcbaO tho
for the telescope; in other words, turn
from the lower to the higher velOcities
The ordinary rate of human travel on
foot is estimated at twenty miles day.
But men have not been content with this
snail's pace: They first increased their
speed by the use of horsepower, which
gave them an average rate Of thirty or
forty miles day. Then they devised
steam power, the average locomotive rate
OF which no one as yet is able to specify.
Already the newspapers have announced
IN large capitals, the astounding fact
'Ar0ot7ad the earth IN seUenty,tfoetr days!'' a
feat which, only few years since, required
tenfold the time. Enormous, however, as
this rate OF travel seems to be, when COM
pared in the aggregate with former rates,
1t will be shOrn of much of its apparent
glory when small portions of the average
are compared with other well-knoWn
rates; for twenty-five thousand miles
divided into seventy-four parts, gives the
average of not quite three hundred and
forty miles a day, or fourteen miles per
hour. This rate was not only attained, but
even exceeded, by many a Juvenile savage
Of the Pacific islands, 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 estimated, 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, indi-
Gated by the average of Round the world
in seventy-four days. is far from being
the highest attained in travelling. Forty
miles per hour, equivalent to about one
thousand miles day, is not uncommon,
although, if any one will look out of the
car-WindOW at the rugged sides of a rail
road-cut, while travelling past them at 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 En-
glish railways wero run at the fearful
speed Of mile a minute and, on q special
occasion, when sudden emergency de-
manded 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 pain
fully suggestive of accident, to another
which is far greater, yet gentle and pleas
ant. Any one who will watch the play of
woodlands axe at the distance of
quarter of mile, will be amused, no mat
ter how often it has been witnessed, to
note the difference in time between the
fall of the axe and the sound of the blow
reported to the ear At that distance the
stroke is heard while the axe is lifted in
the air, ready for the succeeding blow. A
careful measurement of the velocity of
sound shows that, although it varies much
with varying circumstances, it travels usu-
ally at the rate Of about five miles a min
ute. This speed is oftentimes made visi
BILE in the flight Of cannon-ball; for
although the initial velocity of the ball is
SO much greater than of sound that per-
sons 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
SlackpnS TO less than the Ve1Ocitv of sound