Mining: An Elementary Treatise on the Getting of MineralsLongmans, Green, 1904 - 547 страници |
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Страница 44
... minute ; if the gold is invisible , the veinstone will have to be crushed and assayed . The same observation applies to tin , which is often minutely divided in a very hard rock . --- Case IX . In this case veins have been already ...
... minute ; if the gold is invisible , the veinstone will have to be crushed and assayed . The same observation applies to tin , which is often minutely divided in a very hard rock . --- Case IX . In this case veins have been already ...
Страница 50
... minutes , written thus , 60 ' ; each minute is divided into 60 equal parts , called seconds , written thus , 60 " . Any line drawn from the centre of a circle to its circumference is called a radius . Any line drawn across the circle ...
... minutes , written thus , 60 ' ; each minute is divided into 60 equal parts , called seconds , written thus , 60 " . Any line drawn from the centre of a circle to its circumference is called a radius . Any line drawn across the circle ...
Страница 51
... minutes , will be found the radius figure 0'5000352 ; therefore tangent I 0'5000352 ; or , leaving out I I I the last three figures , = 2 = = = ; or the horizontal I 0'5000 0'5 distance which is radius is twice the vertical distance ...
... minutes , will be found the radius figure 0'5000352 ; therefore tangent I 0'5000352 ; or , leaving out I I I the last three figures , = 2 = = = ; or the horizontal I 0'5000 0'5 distance which is radius is twice the vertical distance ...
Страница 57
... minutes to an hour , the bottom of the hole becomes choked with dirt or the chisel gets blunt ; the rods are then drawn . This is done by means of the winch with a rope over the pulley . There is a claw- hook ( Fig . 75 , 20 ) at the ...
... minutes to an hour , the bottom of the hole becomes choked with dirt or the chisel gets blunt ; the rods are then drawn . This is done by means of the winch with a rope over the pulley . There is a claw- hook ( Fig . 75 , 20 ) at the ...
Страница 77
... minute , and as they are a great weight they force the dia- monds against the rocks , which are abraded ; at the same time the water , issu- ing from the internal tube , carries away the sand that is made , keeping a clean SECTION PLAN ...
... minute , and as they are a great weight they force the dia- monds against the rocks , which are abraded ; at the same time the water , issu- ing from the internal tube , carries away the sand that is made , keeping a clean SECTION PLAN ...
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air-current air-road anemometer bars bore-hole boring bottom brattice brick cage capstan cent centre coal measures coal-dust Coal-field colliery compressed conductors cubic foot cylinder Davy lamp depth detonator dirt distance drill driven drum electric engine fire-damp flame flange foot foot-pounds friction fulminate of mercury furnace gauze ground gunpowder haulage heat hole hoppet inches in diameter incline iron ironstone lamp length lifted load lower machine Millstone Grit mineral mines minute outcrop pass Permian pillars pipe piston pit-bottom plate props pulley pump road rocks rods roof rope rule safety-lamp sandstone screw seam of coal shaft shale shown in Fig shows side sinking sometimes speed spur-gearing square inch stalls steam steel stone strata stroke surface temperature thick timber tons tubbing tube upcast valves vein velocity vertical waggons Warwickshire water-gauge wedge weight wheel wire yards
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