MACHINE. — The engine for drawing coals. Winding engines or machines are usually constructed to work with high pressure steam, but condensing-engines, although in the first instance more expensive, are much cheaper in the end, the repairs of the boilers being comparatively trifling, and the labour in firing and cost of coals less. A ready rule for calculating the power of a high pressure engine, the diameter of the cylinder, and the pressure of steam on the piston being given, is as follows :—

Square the diameter of the cylinder in inches, multiply by the pressure of steam in lbs. per square inch, and divide the product by 400.

In the case of the condensing-engine, multiply by the sum of the steam and vacuum pressure.

MAIN-CRAB. — (See Fleet.)

MAIN-ENGINE. — The pumping-engine, until recently usually a condensing beam-engine. The following is the rule for finding the quantity of water which an engine will pump from a given depth :—

Let H = Horse-power of engine.
   F = Depth of pit in fathoms.
   G = Quantity of water in gallons per minute.
Then = G.

and having any two of the above data given, the third can be found.

MAIN-ROPE. — (See Engine-plane.)

MAKINGS. — Small coal made in kirving and nicking.

MAN-DOOR. — (See Door).

MAN-HOLES. — (See Refuge Stalls).

MARROW. — A partner.

MASTER-SHIFTER. — The person in charge of the shifters. (See Shifters, Shift.)

MASTER-WASTEMAN. — The person who has charge of the wastemen. (See Wasteman, Waste.)

MATCH. — A small piece of candle end or greased twine or tape placed horizontally beneath the end of the kitty used to ignite the powder in blasting. When everything is ready, the workman applies a light to the point of the match, which he has made of sufficient size, and placed in such a position as in burning to occupy time enough before the flame reaches the kitty to allow him to retire to a safe place. Frequently where lamps are used a wire inserted through the gauze and heated to redness in the flame of the lamp is used to ignite fuse, substituted for the kitty.

MAUL, MELL. — A hammer used in setting props, driving wedges to force down stone or coal, and in drilling in stone to drive in the drill; also, with a long handle, to draw props.

MAVIES. — It may be; perhaps.

MEETINGS. — "Where the cages pass each other in the shaft, or where the full and empty sets pass each other on a self-acting plane." (Nicholson.)

METAL. — Shale. (Plate, of the lead mining districts.)

METAL RIDGE OR METAL RIG. — (See Creep.)

MILLSTONE GRIT. — Hard coarse post with small pebbles of quartz lying immediately at the bottom of the coal measures.

MISTRESS. — An oblong box, wanting the upper part of the front side, and carried upright, having a round hole in the bottom to allow the candle to be raised (as it burns down) through clay to support it, and keep the hole close. The use of the mistress is to carry a lighted candle in a current of air. Used by the drivers.

MONKEY. — A self-acting lever placed between the rails at the top of an inclined plane, the heavy end of the lever being to the dip and the light end rising above the level of the tub axles. On ascending the plane, the axles depress and pass over the light end, which so soon as they have passed is raised again, and prevents any running back of the set. The same object is gained by having a side chock pointing to the rise, and balanced so as to lie diagonally over the rail; it is pressed back by the tubs in passing, and afterwards falls back into its place behind the last wheel of the set.

MOTHERGATE. — The continuation of the rolleyway beyond the flat into the workings. At a future period converted into rolleyway.

MUSHY. — Coal or shale soft and friable, often found near a hitch.