with the strike. In some regions, such as the
anthracite region of Pennsylvania, tlie term
gangway is used instead of level, and the main
gangway is called the entry. Chambers and
drifts are usually run oH' from the levels.
LEVELERS. An ultra-reform party which
aro^e in the army of the Long Parliament, when
the army overawed that body, and sent Charles I.
to Hampton Court in 1647. They determined to
level all ranks and establish an equality of titles
and estates throughout the Kingdom. Several
of the officers belonging to this party were cash-
iered in 1649; and on the departure of Cromwell
for Ireland, at the close of that year, they raised
mutinies in various quarters, which were sup-
pressed by Fairfax with bloodshed. One of their
works. The Leveler, or the Principles and Max-
ims Concerning Government and Religion of
Those Commonly Culled Levelers, shows that in
politics their fundamental principles included :
(1 ) The impartial authority of the law; (2) the
legislative power of Parliament; (3) absolute
equality before the law; (4) the arming of the
people for securing the enforcement of the laws,
and the protection of their liberties. In religion
they claimed: (1) Absolute liberty of conscience;
( 2 ) freedom for every one to act according to
his knowledge, even if this knowledge should be
false; (3) religion to be considered in two
aspects — one as the correct understanding of
revelation, which is a private affair, the other
as its effects manifested in actions, which are
subject to the authorities; (4) they condemned
all strife on matters of faith and forms of wor-
ship. This sect disappeared at the time of the
Restoration.
LEVELING. In surveying, the operation of
ascertaining the different elevations of objects on
the surface of the earth. Leveling is employed
to find the relative elevation of points a con-
siderable distance apart, to obtain the profile of
a line, or to establish a grade. These objects
may be more or less intermingled in any piece
of work. For convenience of discussion, leveling
operations may be broadly classed into common
spirit-leveling, trigonometrical leveling, and pre-
cise spirit-leveling. The difference between the
first and the third classes lies chiefly in the de-
gree of accuracy with which the work is per-
form<^d. Spirit-leveling operations are essentially
the same whatever their object may be. For ex-
ample, suppose it is required to determine the
difference in elevation between two distant points.
The instruments are the level and the level-
rod, forms of which are illustrated on the Plate
of Engi.neerino IN.STRIMENTS. The rod is set
up on the starting-point and the level is set up
a convenient ilistance away in the direction of
the otlier point, and where a plain view is had
of the level-rod. When the level is adjusted, the
levelman takes a reading on the graduated level-
rod and records it in his note-book. The rodman
then moves his rod to a point ahead of the level,
and the levelman takes another reading, which he
likewise records. This reading is called a fore-
sight, in contradistinction to the first reading,
which is called a backsight. The levelman then
removes his level to a point ahead of the second
position of the rod. sets it up. adjusts it, and
takes a backsight reading on the rod. This being
recorded, the rodman moves to a new position
ahead of the level, where he sets up the rod on
which the levelman takes a foresight reading,
and then moves again to a new position ahead
of the rodman. By means of sufficient repetitions
of these operations the distance between the two
points whose dilTerences in elevation are to be
determined is traversed, the last reading being
taken with the rod set up on the finishing-point.
When the final reading has been taken a simple
calculation in addition and subtraction per-
formed on the recorded readings gives the level-
man the result he desires, which is the difference
in elevation between the starting and the finish-
ing points. In conducting such a series of read-
ings as has been described, the attempt is always
made to make the lengths of the backsight and
foresight for each setting of the level as nearly
equal as possible, and also to make them as
long as possible consistent with clearness of sight.
It is in this way that the profile of the route
of a railway line or highway is determined.
Having obtained the natural profile, the engineer
in railway or road building has to cut down
the irregularities by means of one or more uni-
form gradients. These he determines first on
paper, figuring out the rate of ascent or descent.
Supposing that he has determined a grade of
one foot in a hundred feet, then each succeeding
inteivening point is one foot higher or lower,
according to direction, than the preceding point.
The levelman then re-runs his line of levels
according to this adopted gradient, and marks
on the stake at each intervening point the eleva-
tion at which its top is above or below the
adopted grade-line.
Precise spirit-leveling is performed in exactly
the same way, except that larger and more per-
fect instruments are employed and more care is
taken in making the readings and performing
other necessary operations.
In trigonometric leveling the difference of ele-
vation between two different points is determined
by measuring the vertical angle, the horizontal
distance between the two points having been pre-
viously measured by triangulation. ( See Slr-
VEYING.) This distance and the vertical angle
give the necessary data for the calculation of the
difference in elevation by the familiar rules of
trigonometry. This method of leveling is liable
to error from refraction, and is far less precise
than spirit-leveling when the latter method is
practicable. Elevations of different points, as the
tops of mountains, are often measured by barom-
eter or by noting the temperature at which water
boils. These are not exact methods, and are used
only in exploration work. See Hypsoiietry.
LEVEN, le'v'n. Loch. A picturesque lake
in the east of Kinross-shire, Scotland (ilap:
Scotland, E 3). It is oval in shape, about four
miles long and two wide. It is celebrated for
its trout. Loch Leven Castle, in which, in 1.567,
Queen Mary was imprisoned and forced formally
to abdicate the throne, and whence she escaped
in 15CS. is one of the islets in the lake.
LEVENSHTJLME, le'v'nz-hulm. A manufac-
turing town in Lancashire, England, three and
one-half miles southeast of Jfanchester (Jlap:
England. D 3). Population, in 1891, 5500; in
ion I. 11. .500.
LEV^QUE, IS'vak'. .lE.>r Cii.irles (1818-
1900). A French philosopher, born at Bordeaux.
He was a pupil of the Normal School, taught at
Besancon, and studied in Athens (1847-48)'
Page:The New International Encyclopædia 1st ed. v. 12.djvu/187
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LEVEL.
169
LEVEQUE.