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amount angle beds body boiler bottom breast built called carried cars chutes close coal connected cylinder depth diameter direction distance driven engine equal face feet field force give given headings heat hole horizontal inches inclined increase indicated iron length less limestone loaded lower material matter means measures method mining minute move nearly necessary opening parallel pass pillars piston pitch placed plane position pounds pressure produced props rail reached removed result roads rocks roof rooms rope seam shaft shown shown in Fig shows side sinking slope sometimes space square inch steam strata stroke surface taken temperature thick timber track tubes turned upper usually valve vertical volume wall weight wide
Página 30 - Since, according to the third law of motion, every action has an equal and opposite reaction, we call that force which acts as an equal and opposite force to the pull of the string the centrifugal force, and it acts away from the center of motion.
Página 19 - of the free air actually compressed. Theoretically, this volume is equal to the area of the piston, multiplied by the length of the stroke. Actually, however, owing to imperfections in workmanship, the air does not begin to compress at the instant the piston begins its stroke. The point where the compression begins is indicated on the diagram by the
Página 38 - Lead.—A valve is said to have lead when it commences to open the steam-port just before the piston reaches the end of the stroke. The amount of lead is measured by the distance between the edge of the valve and the edge of the port from which the valve is traveling. In
Página 32 - be less steep than the slope of the valley, then the V's, as they are often termed by miners, will point upwards (see Fig. 413), those formed by the newer .beds appearing in a superior position and extending highest up the valley, as A
Página 29 - now be explained. Suppose that the body is revolved horizontally, so that the action of gravity upon it will always be the same. According to the first law of motion, a body put in motion tends to move in a straight line unless acted upon by some -^ other force, causing a change in the
Página 24 - to 54° that it took to raise the temperature from 52° to 53°. The unit quantity of heat is the quantity required to raise the temperature of a pound of water from 62° to 63°." This unit is called the British thermal unit, or BTU §18 STEAM AND STEAM-BOILERS.
Página 53 - per cent, of volatile matter, and the material volatilized includes a large proportion of burning and lubricating oils, much larger than the above kinds of bituminous coal ; whence it is extensively used for the manufacture of such oils. It graduates into oil-producing coaly shales, the more compact of which it much resembles.
Página 30 - inch face. They consist of a cylindrical box of metal, with a top of thin, elastic, corrugated metal. The air is removed from the box. When the atmospheric pressure increases, the top is pressed inwards, and, when it is diminished, the top is pressed outwards by its
Página 14 - The work done in one stroke of a pump is equal to the weight of a volume of water equal to the volume displaced by the piston during the stroke, multiplied by
Página 7 - gal. per hr. (1414) The lever of a hydraulic press is 7£ feet long, the piston-rod being 1 foot from the fulcrum. The area of the tube is £ a square inch ; that of the cylinder 80 square inches. What weight may be raised by a force of 80 pounds applied at the end of the lever ? Ans.