A Treatise on Mine-surveying |
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Page 11
... construction of iron chains is usually No. 8 W.G .; that used for steel chains is No. 12 , or No. 8 W.G. The hundredth part of the chain is called a link , and is equal to 0.66 foot or 7.92 inches . All calculations with chains and ...
... construction of iron chains is usually No. 8 W.G .; that used for steel chains is No. 12 , or No. 8 W.G. The hundredth part of the chain is called a link , and is equal to 0.66 foot or 7.92 inches . All calculations with chains and ...
Page 49
... construction of the instruments , the bearing of one and the same line is found to vary when determined with different dials . By observing the line of orientation , the error of each dial may be determined , and applied as a constant ...
... construction of the instruments , the bearing of one and the same line is found to vary when determined with different dials . By observing the line of orientation , the error of each dial may be determined , and applied as a constant ...
Page 61
... construction of the sights , the use of horse hairs is avoided , as they are continually getting burnt by a flaring candle underground . In place of the ordinary horse - hair sights , the split - sight is adopted . There is a narrow ...
... construction of the sights , the use of horse hairs is avoided , as they are continually getting burnt by a flaring candle underground . In place of the ordinary horse - hair sights , the split - sight is adopted . There is a narrow ...
Page 78
... construction . In the Harz mines , instead of the cord , a thin brass chain is used . It is 10 metres in length , and is provided with a hook at one end . Every metre is indicated by a brass tag . The chain is wound on a reel , and used ...
... construction . In the Harz mines , instead of the cord , a thin brass chain is used . It is 10 metres in length , and is provided with a hook at one end . Every metre is indicated by a brass tag . The chain is wound on a reel , and used ...
Page 79
... construction . If the cord is in- clined at an angle B A C ( Fig . 27 ) , the hair will not coincide with zero , but will give the angle DHE , which represents the angle of in- clination of the cord . For since AHD + DHE = a right angle ...
... construction . If the cord is in- clined at an angle B A C ( Fig . 27 ) , the hair will not coincide with zero , but will give the angle DHE , which represents the angle of in- clination of the cord . For since AHD + DHE = a right angle ...
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Common terms and phrases
accuracy accurate adjusted back-sight base-line bearing bore-hole brass calculated centre chain City Guilds clamped clinometer coal colliery collimation colour compass compass-box contour lines cord corner cosec cotan cross-wires curve determined direction distance employed equal error fathoms feet fixed fore-sight glass graduated ground height hole horizontal circle inches inches in diameter inclination instrument intersection latitude length lode magnetic bearing magnetic meridian magnetic-needle marked means measured method metres mine-surveying miner's dial mines needle observations obtained offsets Ordnance Survey parallel parallel ruler perpendicular placed plane plate plotting plumb-bob plumb-line plummet position protractor represented right angles safety-lamp scale seam shaft side Silver King spirit-level square staff station station-line strike and dip surface surface-surveys survey tacheometer tacheometry taken tangent screw telescope theodolite transit-theodolite traverse triangle tripod tube underground vernier vernier-plate vertical angles wire yards zero