A process for creosoting timber (such as track sleepers) to extend its
useful life. The timber is first dried, then placed in a cylinder and
subjected to partial vacuum, and finally impregnated with creosote under
pressure. See also:open-tank method; timber preservation.
Nelson
The maximum acceptable difference between the means of two determinations
carried out by two different laboratories on representative samples taken
from the same bulk sample after the last stage of the reduction process.
BS, 1
a. A trigonal mineral, PbFe3+3 (AsO4 )(SO4
)(OH)6 ; crystallizes in green to black rhombohedra.
b. A mineral group.
Any style of cutting with a large table joined to the girdle by one, or
possibly two, bevels and a pavilion that may be step cut, brilliant cut,
or any style. Used mostly for opaque stones and intaglios. Bevel-cut
shapes include round, square, rectangular, oblong, oval, pendeloque,
navette, heart, diamond, horseshoe, shield, pentagon, and hexagonal
shapes. The style is used predominantly for less valuable gems.
Syn:table cut
a. A cone-shaped gear encircling the drive rod in a diamond-drill swivel
head, which meshes with a matching gear attached to the drive shaft from
the drill motor. By means of these gears, the drill-string equipment can
be made to rotate. Syn:miter gear
b. Any gear, the teeth of which are inclined to the shaft axis of the
gear. Long
c. A gearwheel that transmits power between two shafts that meet at an
angle. If at a right angle and the wheel is of the same size, it is called
a miter gear. Crispin
A tetragonal mineral, (Ca,Pb)Bi2 (CO3 )2 O2 ;
forms minute tetragonal crystals and earthy masses; a secondary bismuth
mineral.
a. A noncoring or blasthole bit. Long
b. A CDDA standard-size noncoring bit having a set outside diameter of 1
in (2.54 cm). Normally referred to as a 1-in B.H. bit. Long
The layer of a soil profile in which material leached from the overlying
A-horizon is accumulated. Syn:zone of accumulation;
zone of illuviation. See also:A-horizon
See:bearers
Eng. A timber stay or beam in a shaft. See also:bearer
byat.
The optical character of crystals belonging to the orthorhombic,
monoclinic, and triclinic systems, which exhibit double refraction, but
have two directions of single refraction and isotropy, i.e., two optic
axes. CF:uniaxial
A mineral that has crystallized in the orthorhombic, monoclinic, or
triclinic system and hence has two optic axes. CF:uniaxial stone
An aerial ropeway using stationary track ropes along which carriers are
hauled by an endless haulage rope. See also:aerial ropeway
Nelson
A winding drum with a cylindrical middle portion and two conical outer
portions; used sometimes where the weight of the winding rope is large
compared with the coal or mineral load. The heavily loaded upgoing rope
winds on the small diameter, while the downgoing rope winds off the large
diameter. The effect is to compensate for the heavy torques due to rope
unbalance and acceleration. See also:cylindroconical drum;
winding drum. Nelson
A monoclinic mineral, CoSO4 .7H2 O ; melanterite group;
flesh-red to rose-red; esp. in crusts and stalactites.
Syn:cobalt vitriol
One that separates objects moving in a single lane and delivers them to
two lanes of movement.
Nongelatinous permissible explosive; used in coal mining. Bennett
N. of Eng. A built-up pillar of stone or other debris in a working place
or heading to support the roof; e.g., "bigging the gob" means building a
pack in a worked-out place.
Bits set with diamonds as large or larger than eight stones per carat in
size. Long
A monoclinic and triclinic mineral, LiAlSi2 O6 .H2 O;
may be in zeolite group; colorless or white; in granular aggregates with
eucryptite in lithia pegmatites.
A transducer capable of transmission in either direction between its
terminations. Syn:reversible transducer