a. An angular recess cut in the ends of a crossbar of a timber set to fit
over a corresponding wedge in the upright posts. With the advent of steel
arches, the craft of notching is becoming extinct.
See also:Welsh notch
b. Eng. See:let into
c. A small weir made for use in measuring flow in laboratory models of
hydraulic structures. See also:measuring weir
d. A hollow formed by the undermining of a cliff, as a result of wave
erosion and/or solution. Schieferdecker
Locally increased stress at that point in a structural load-bearing member
where the section changes at a sharp angle. Hammond
A machine tool in a steel-fabrication shop used to strip the flanges from
the ends of rolled steel joists. Hammond
a. A method of excavating in a series of steps. Standard, 2
b. Cutting out various shapes from the edge of a strip, blank, or part.
ASM, 1
Alternative term for factor of stress concentration in fatigue or fatigue
strength reduction factor. Roark
These words refer to the time of the location and commencement of the
tunnel and not to the respective times of the discoveries of the various
veins in the tunnel. Ricketts
A longwall method of working coal seams in which the trams run on a rail
track along the face and are hand loaded at the sides. It follows that the
system can be adopted only in relatively thick seams where the trams can
travel along the face without any roof ripping. The method is now replaced
by face conveyors. Syn:Barry mining
See:garnierite
A monoclinic mineral, (Cu,Ag)21 As10 ; pseudotetragonal;
forms steel-gray granular aggregates; at Cerny Dul, Czech Republic.
a. A dense, hard even-textured, light-colored cryptocrystalline siliceous
sedimentary rock, similar to chert but characterized by dominance of
microcrystalline quartz over chalcedony. It was formerly believed to be
the result of primary deposition of silica, but in the type occurrence
(Lower Paleozoic of the Ouachita Mountains, Arkansas and Oklahoma) it
appears to be a thermally metamorphosed bedded chert, distinguished by
characteristic polygonal triple-point texture. The origin of novaculite
has also been ascribed to crystallization of opaline skeletal material
during diagenesis. The rock is used as a whetstone.
See also:Arkansas stone
ouachita stone. AGI
b. A term used in southern Illinois for an extensive bedded chert.
AGI
c. A general name formerly used in England for certain argillaceous stones
that served as whetstones. AGI
a. The inner part of a large mold, corresponding to the core in small
work. Standard, 2
b. The bottom or drag of a molding flask, as distinguished from the cope.
Standard, 2
A gas that is injurious to health. BS, 8
A tabular refractory shape used in a ladle, with a hole through which
steel is teemed at the bottom of a ladle, the upper end of the shape
serving as a seat for the stopper. ARI
In metal mining, one who operates a hydraulic giant or monitor (nozzle)
used to direct a high-pressure stream of water against a bank of
gold-bearing gravel to erode and force the gravel into sluiceboxes, where
the gold separates out and is caught by riffles (cleats).
Syn:giant tender
A modification of the basic Bessemer process. The main feature is the
shortening of the blow by increasing the pressure of the blast as much as
possible. Normally, the melt is cooled by the addition of scrap or iron
ore, but it is claimed that a fairly high temperature can be maintained
without an undue increase of the nitrogen content, so that ladle skulls
can be avoided. Osborne
A letter name specifying the dimensions of bits, core barrels, and drill
rods in the N-size and Q-group wireline diamond drilling system having a
core diameter of 47.6 mm and a hole diameter of 75.7 mm.
Cumming, 2
A Canadian standard noncoring bit having a set diameter of 2.940 in (74.7
mm). More commonly called a 2-15/16 N drill-rod bit. Long
A bridge or roof truss that has parallel upper and lower chords and an
arrangement of web members consisting of tension diagonals and compression
verticals, with the vertical struts separating the panels. Also known as a
Pratt truss. See also:Warren girder
a. Mid. A block of wood about 12 in (30.5 cm) square, for throwing mine
cars off the road in case the couplings or ropes break. Fay
b. See:stopblocks
The use of a nuclear explosive for fracturing and fragmenting large
volumes of ore underground into rubble chimneys, in preparation for
block-cave-type mining or in-situ leaching. SME, 1