Maps and survey . 3. Mark on tripod. 4. Alignment sight on tripod. Invar Tape Base Apparatus. Department of Geography,Cambridge University. SURVEY INSTRUMENTS 197 precautions are taken to control at frequent intervals the lengthsand the graduation of the staves. Invar tape or wire base apparatus. As a result of experience in the field certain modificationshave been made in the apparatus as it was designed by at the International Bureau at Breteuil. We havealready mentioned the improvement in the levelling arrange-ments, which make it possible to measure up slopes as great asone in
Maps and survey . 3. Mark on tripod. 4. Alignment sight on tripod. Invar Tape Base Apparatus. Department of Geography,Cambridge University. SURVEY INSTRUMENTS 197 precautions are taken to control at frequent intervals the lengthsand the graduation of the staves. Invar tape or wire base apparatus. As a result of experience in the field certain modificationshave been made in the apparatus as it was designed by at the International Bureau at Breteuil. We havealready mentioned the improvement in the levelling arrange-ments, which make it possible to measure up slopes as great asone in three. The straining trestles and the mark tripod havealso been improved. The apparatus which we illustrate wasdesigned at Cambridge, after learning the experience of measure-ment on the Lossiemouth and Semliki bases. It was made inthe Observatory workshop, largely by the skill of Mr GordonDobson, , of Gonville and Caius College. (Plate XXIV.) The straining trestle has, as is now usual, one leg prolongedto res
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectsurveying, bookyear19
