Transactions . Heller A Brightly*8 Sunflower, Front View, with an Extension-Tripod. wooden rod touches the perimeter of the tunnel, while the dis-tance is read with a vernier at the center of the disk. Thedistances are taken at any desired number of angles around thewhole rdisk? and are plotted conveniently with a protractor.(See Fig. 163.) The time required to measure a section of thetunnel is from six to ten minutes. The weight of the disk in-cluding all attachments is 10 pounds, and the tripod-head with L02 NOTES ON MINB-SURVBYINQ INSTRUMENTS. an extension-leg tripod weighs 10 j pounds, mak
Transactions . Heller A Brightly*8 Sunflower, Front View, with an Extension-Tripod. wooden rod touches the perimeter of the tunnel, while the dis-tance is read with a vernier at the center of the disk. Thedistances are taken at any desired number of angles around thewhole rdisk? and are plotted conveniently with a protractor.(See Fig. 163.) The time required to measure a section of thetunnel is from six to ten minutes. The weight of the disk in-cluding all attachments is 10 pounds, and the tripod-head with L02 NOTES ON MINB-SURVBYINQ INSTRUMENTS. an extension-leg tripod weighs 10 j pounds, making a totalweight oC 20J pounds. There are two measuring-rods, 8 and11 feel long. The instrument is also useful for testing masonrywork after the centers are struck. Plummet-Lamp.—Eckley B. Coxes plummet-lamp Jwas de-scribed by Dr. Raymond, then 1resident of our Institute, and Fio. Heller & Brightlys Sunflower, Side View. its use explained by Mr. Coxe himself in papers read before themeeting of February, 1873,* and was soon published in sev-eral journals. The lamp was made by Heller & Brightly, andwas contrived for use in accurate mine-surveying to take theplace of the open mine-lamp set (if not, as too often happened,overset) on the ground, or of the mere string of a plumb-bob * Trans., I, 378. NOTES ON MINE-SI i;\ EYING [NSTR1 mini-. 103 with or without a Light or a white Burface behind it. The plum-met-lamp, aa eventually made, reeta i»y trunniona on a horizontalM compensating ring, which at points .*<» from the trunniona iahung l»v two light short chaiue from a <r the minetimber over a station, or Into a wooden plug inserted in a hole drilled in the coal or rock root. Mr. Coze found that with the plummet-lamp two persona can make a very accurate Burvej[uic
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
