Railways

3924

Rainfall

of its motion, no matter what movement
may be impressed on its support, a principle
which has already been successfully used in
vessels to prevent or minimize pitching and
rolling, and in aircraft (see GYROSCOPE).
Since 1907 many experiments have been made
on this line. Somewhat extravagant claims
have been made for the gyroscopic type of
monorail by those who think that it is des-
tined eventually to revolutionize traffic, and
it has been predicted by some that the rail-
way train of the future may be run on a
loosely hung cable, even across deep gorges,
doing away with all costly systems of con-
structions, embankments, bridges, and the
like.

Mountain Railways.—Railways passing
through mountainous districts constitute a
special class on account of the steep grad-
ients necessitated, the considerable heights
which often must be surmounted in a lim-
ited distance, and the special dangers, such
as avalanches, torrents, and landslips, which
must be guarded against in construction. The
rack railway is the commonest system where
the gradient of the line is too steep to allow
the load or train to be hauled up in the usual
manner by self-propelled vehicles, such as
steam-engines and electric motors, or to al-
low of loads being lowered by means of
ordinary brakes attached to the running
wheels of the train. On a bed of coarse gravel
steel rails are laid on steel sleepers with the
rack in the center of the line. This consists
essentially of some form of rackwork or sys-
tem of teeth, running longitudinally with the
railway, into which cog wheels on the engine
Sear, thus providing a positive grip for these
toothed driving wheels to which power can
be applied for hauling up the loads, and
powerful band brakes can be attached for
lowering the load. On some lines, as the Gor-
nergrat and the Jungfrau in the Alps, elec-
tricity is the motive power. Cable railways
are used up to a maximum gradient of 650 in
1,000, the Beatenberg, Lugano, Stanzerhorn,
and other Alpine lines being of this construc-
tion.

Military Railways may be classified as (i)
those that are built and operated within the
field of the enemy's observation and fire—
combat railways; and (2) those that are
built beyond the range of hostile observation
and fire—supply lines.

Combat railways are practically always of
narrow gauge and in most cases are of port-
able track similar to that used in mines and
industrial works. They must be capable of

transporting guns, ammunition, and other
supplies, as well as of bringing up reinforce-
ments rapidly, conveying working parties to
and from work, and removing sick and
wounded to the rear. Supply railroads are
constructed to convey troops and supplies
from the base to the front in time of war, and
to connect permanent camps with the nearest
existing railway. They vary from a light
portable track to a standard gauge line, the
principal considerations in their construction
being the amount of troops, supplies, and ani-
mals to be handled, the time available for
construction, and the amount of transporta-
tion necessary to place supplies on the work.
See also RAILROADS.

Rain. Sec Rainfall.

Rainbow. When the sun shines on falling
rain, a rainbow, or arc of prismatic colors,
is seen on the rain. The phenomenon is due
to the combined effects of refraction and in-
terference of the solar rays as they pass
through the falling raindrops. The arc has a
radius of from 40° to 42^°, and the colors
are arranged in the order of the spectrum—
red being outside, and then orange, yellow,
green, blue, indigo, and violet. The purity of
the color phenomena depends on the size
and uniformity of the drops of rain. The
amount of the circle visible at any moment is
determined by the altitude of the sun. The
ordinary or primary rainbow is caused by one
reflection and two refractions of the rays of
light from the inner surfaces of the raindrops
and through them, while the secondary bow
is occasioned by two reflections and two re-
fractions.

Rainbow Trout, a richly colored Califor-
nian trout (Salmo irideus). It has been ex-
tensively acclimatized in the Eastern United
States and elsewhere. It is also the name of
the Rocky Mountain trout.

Rain Crow, an American tree cuckoo (ge-
nus Coccyzus), especially the Yellow Billed
Cuckoo (C. americanus). It is supposed to
foretell rain by its cries, heard in lowering
weather.

Raines, John (1840-1909), American legis-
lator, was born in Geneva, N. Y. He was a
member of the New York assembly (1881-2
and 1885), a State senator (1886-9, 1894-
1909), and a member of Congress (1889-93).
He was the author of the New York liquor
legislation known as the 'Raines Law,' which
stipulated that liquor could be sold on Sun-
days in New York State only by licensed ho-
tels containing at least ten bedrooms.

Rainfall is the water that is precipitated