Transactions . screws, with a portion of the triangular levelihg-frameattached. The space marked 1 on the sectional elevation, be-tween the carrying-plate and the screw portion above, is in-tended to give room for the fingers when manipulating thelarge heads of the screws m and mf of Fig. 13. To Connect Underground Workings with the Surface. The mode of proceeding in connecting the first line in anunderground heading or tunnel leading from a shaft into a 906 \\ [MPROVED FORM OE TRANSIT-TII EODOLITE. mine is as follows: A downcast shaft, Fig. 21, 18 selected(work being suspended in it), and at
Transactions . screws, with a portion of the triangular levelihg-frameattached. The space marked 1 on the sectional elevation, be-tween the carrying-plate and the screw portion above, is in-tended to give room for the fingers when manipulating thelarge heads of the screws m and mf of Fig. 13. To Connect Underground Workings with the Surface. The mode of proceeding in connecting the first line in anunderground heading or tunnel leading from a shaft into a 906 \\ [MPROVED FORM OE TRANSIT-TII EODOLITE. mine is as follows: A downcast shaft, Fig. 21, 18 selected(work being suspended in it), and at a convenienl distance fromthe bottom of the shaft, along the main road, A, or at the firslbend of it, a permanenl station is formed by driving a steelor copper peg, 1] in. in diameter and 12 in. long, into the floorof the mine a1 the point selected: but if the floor consists ofhard rock, a hole is drilled and the metal peg is firmly corresponding hole is also made in the roof of the heading, Fig. Sectional Elevation of Central Portion of Table and Carrier-Plate,and of Portions of the Locking-Frame. vertically over the metal peg or station, and another metal pegwith a hole in its low^er part is driven into the roof and properlyadjusted; so that, when a plumb-bob line is suspended, the finepoint of the bob coincides with a counter-sunk hole made in thecenter of the metal peg or station. It would be convenient to have two stout wooden benches,4 ft. in length, 14 in. in width, and 2 in. in thickness, with fourlegs each, and with strong steel short spikes in all of the of the benches may have a height of 20 in., and the other i \\ I MPROVED I ORM I NlANSIT-1 IIEOD0L1 I E. 907 Buch a height as would, with an illuminated box to be placedupon it, amount to L9| in., or other convenient height Thehigher of these benches should be placed with the inner edgeof one of the longest sides to coincide with a vertical linewhich would tall upon the center of the metal peg
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
