The republic. [volume] (Washington [D.C.]) 1849-1853, 1850-07-15

Fast Travelling on Railroads.
correspondent wishes TO know why the speed
OF railroad travelling in this country is not in
creased as III En- gland. He states that the average
OF speed here is but fifteen miles hour while in
Great Britain II Is not less than forty We think
he IL somewhat mistaken. The average speed IN
the United States is certainly twenty miles an hour,
while In England II is not over twenty five. He
has COMPOUNDED the express trains with the ordi
nary trains he would not have set down the speed
of the British railroads at forty miles. Some of the
trial trains here run at velocity of seventy miles
an hour; but this is by means common occur
renee, the ordinary speed by these trains being
about thirty miles
The principal railroads Of the United States run
their passenger trains fast as those of England
run, and il Is only roads of secondary inn
portance that the British trains have the advantage
over ours The speed OF the firstclass cars, on the
London and Liverpool road, ID twenty five miles,
including stoppages; on the London and South
, ampton il is twenty four miles, including stop
pages The velocity of the evening trains between
here and New York is about twenty two miles, in
Guiding stoppages; on the Erie railroad it is be-
, tween twenty five and thirty and on the Great
. Western. between Albany and Boston, it is very
nearly great Occasionally trains have been run
nearly all these roads at velocity greater
than the usual express trains in England and on
trial trips speed has been attained nearly, if not
quite us great on the British roads. That
1 higher velocity is not ordinarily employed is owing
to the increased danger of accidents, and to the
rapid ratio at which the and tear of the road
progresses under the accelerated speed.
We can best illustrate this augmented wear and
) tear by endeavoring to obtain definite idea of
what speed of seventy miles per hour means
Seventy miles an hour is one hundred and five feet
every second; that is the passenger is carried
thirty five yards between the beats of common
clock. When two trains having this velocity pass
each other, the relative speed will be doubled and
if one of the trains seventy yards long, it
would flash by in a single second. II the driving
wheel OF the locomotive is seven feet in diameter
the wheel would revovc five times in passing over
iv Eyat
second To produce single revolution OF the
} wheel, the piston rod must move backwards and
forwards once; hence its motion will divide every
second INTO ten equal parts. The valve must, in
steam escapes at every opening of the valve there
must be ten such escapes III every second. But a
Y locomotive has ten cylinders, and the discharge
from one is intermediate between two successive
discharges from the other; consequently there are
twenty discharges OF steam in every second, each
puff having the twentieth of a second between it
and that which preccdes or follows it. Passengers
! have heard these discharges when the locomotive
Is moving slowly, at starting, and will recognise
them by their sounding like quick cough gasp.
{ Some idea Of the enormous rapidity of the work
ing parts OF the engine may be obtained by re-
membering that, at speed of seventy miles, there
! arc twenty OF these coughs per second.
Nor is this all. Though the driving wheels of
/ large locomotives seven feet in diamaer, the
bearing wheels not more than three But
driving wheel revolves when at speed Of seventy
miles, five times each second, hence the bearing
wheels must revove twelve times. A cannon ball,
1t has been computed moves at rate of 26, 500 feet
per minute, which is equal to 300 miles per hour
4 train, therefore, moving at TO miles an hour, a
speed frequently obtained by trial locomotives for
short distance, has velocity only four times less
than cannon ball. In stopping such trains the
difficulty is much greater than would be supposed
from the mere difference IN speed between fast train
and ordinary one. The momentum increases
In the ratio of the square OF the speed, and, conse
quently, in checking train, if the speed has been
doubled, four times as many breaks will be re-
CURED; if trebled nine times many. At all times
! the stopping of train increases the OF the
rails IN consequence of the resistance they give to
the momentum fact which may be seen from the
polished and worn appearance OF rails near station
houses. Now, in checking train that moves
enty miles an hour, this wear is nearly nine times
greater than when train moves at the ordinary
u speed of twenty five miles
The accelerated velocity affects also the machine
ny of the locomotive, the cars, and every thing
nected with the train; and augments the cost at
rate much greater than would be popularity sup
posed. The danger of accidents increases also with
the increase Of speed Ii would be almost impossi
bic TO stop train moving at rate of seventy miles,
in time to prevent a collision with another train
! coming from an opposite direction at equal
- locity. For instance if the trains first saw each
! other when three miles apart, only seventy five
seconds would elapsc before they met, or about
minute and quarter; if when two miles apart,
only fifty seconds; if when one mile, only twenty
/ hive seconds. The momentum, in case of any such
collision, would crash locomotive of thirty tons
! in weight as if il were mere egg shell.
These considerations have induced the managers
OF railways to circumference very high rate of
| speed; and think the decision proper one, and
hope il will be adhered TO- Thirty miles an hour is
fast enough for an ordinary traveller to get over the
/ ground