See:brimstone
Large steel mortar in which a heavy steel pestle rolls. Once used in
grinding and amalgamation of gold ores. Pryor, 3
A variation of brattice cloth. See also:brattice cloth
Derb. A road in a coal mine, supported by brattices built on each side
after the coal has been worked out. See also:brattice
A ferroan variety of magnesite used in the manufacture of magnesia bricks.
A monoclinic mineral, (Sr,Ba,Ca)Al2 Si6 O16 .5H (sub
2) O ; zeolite group.
Liquid plus vapor CO2 in cavities in minerals; e.g., quartz, topaz,
and chrysoberyl. The meniscus vanishes under the warmth of the hand.
a. The index of refraction of a crystalline substance is equal to the
tangent of its angle of polarization. Pryor, 3
b. In optics, where light is reflected from a smooth, transparent,
nonconducting surface, it is plane polarized parallel to the reflecting
surface. The angle of incidence for maximum polarization is that angle
whose tangent is the index of refraction of the reflecting substance. This
angle is also called the "Brewster angle."
An impure clay, containing iron and other ingredients. In industry the
term is applied to any clay, loam, or earth suitable for the manufacture
of bricks or coarse pottery. Syn:brick earth
Eng. Small, dirty coal suitable for brick kilns and similar purposes.
Fay
Earth, clay, or loam suitable for making bricks; specif. a fine-grained
brownish deposit consisting of quartz and flint sand mixed with
ferruginous clay; found on river terraces as a result of reworking by
water of windblown material, such as that overlying the gravels on certain
terraces of the Thames River in England. Syn:brick clay
In Wales, patent fuel. See also:briquette
The walling or casing of a shaft.
A curb set in a circular shaft to support the brick walling.
See also:curb
A staging or platform suspended in a sinking shaft on which masons stand
when building brick walling. Syn:walling scaffold
A permanent support for circular shafts. On reaching the rockhead, a firm
ledge is prepared to receive the first bricking curb or ring. The curb is
fixed correctly with reference to the centerline of the shaft. The bricks
are then built upwards from the curb, the space behind being firmly packed
to the rock sides with bricks and mortar. Concrete is replacing brickwork
as a shaft lining. See also:lining; permanent shaft support.
Nelson
Staff. A contrivance used in coal mining to prevent cars from overturning
upon steep inclined planes having a rise of 1 ft in 3 ft or 4 ft (1 m in 3
m or 4 m). Hess
A black, highly carbonaceous slickensided shale with Carbonicola shells,
in the Adwalton stone or Flockton thick coal; also, dirty smudgy coal in
the roof of the Stanley Main in the Snydale-don Pedro area.
Syn:bright cake
a. A rock fragment, cavings, or other obstruction that lodges (either
accidentally or intentionally) part way down in a drill hole (such as in
an oil well). AGI
b. Debris that plugs a borehole at a point above the bottom. Between the
underside of the bridge and the bottom of the drill hole, the borehole is
free of debris. Long
c. To deliberately plug a borehole at a point some distance above its
bottom. Long
d. To form a bridge in a drill hole. AGI
e. In a cave, a solutional remnant of rock that spans a passage from wall
to wall. AGI
f. A device to measure the resistance of a wire or other conductor forming
a part of an electric circuit.
g. A piece of timber held above the cap of a set by blocks and used to
facilitate the driving of spiling in soft or running ground.
h. Refers to the overburden used for spanning the natural gap between the
highwall and the spoil, when such is required to establish a temporary
machine surface standing area closer to the disposal area than that
provided by the virgin ground. AGI
i. In an electric blasting cap, the wire that is heated by electric
current so as to ignite the charge. Nichols, 1
j. Sometimes, the shunt connection between the cap wires.
Nichols, 1
k. A plankway or elevator used in ironworking to convey fuel or ore to the
mouth of a furnace. Webster 3rd
l. A refractory bar, or member, or fire clay placed across the surface of
the batch in a tank furnace near the working end to hold back the scum, or
gall. Mersereau, 2
m. The structure formed by the end walls of the adjacent melter and
refiner compartments of a tank and the covers spanning the gap between the
end walls. ASTM
n. See:air crossing
The time that elapses between the application of current and the fusion of
the bridge wire when using instantaneous blasting caps. Streefkerk
A conveyor that is supported at one end by a loading unit and at the other
end in such a way as to permit changes in the position of either end
without interrupting the operation of the loading unit. NEMA, 2