Maps and survey . 5. Watkin for Compass SketcJiing. 6. Interior of Clinometer. COMPASS AND PLANE TABLE SKETCHING 105 local attraction at the first point, it will probably be differentat the second, and the error will be detected. These remarks apply to strictly local attractions, such asare caused by fairly small masses of iron at close quarters. Insome countries, such as South Africa, the whole ground is full ofmagnetic rocks, and the compass is practically useless. The compass sketch. The principle is exactly the same as in triangulating withthe theodolite. A base is m
Maps and survey . 5. Watkin for Compass SketcJiing. 6. Interior of Clinometer. COMPASS AND PLANE TABLE SKETCHING 105 local attraction at the first point, it will probably be differentat the second, and the error will be detected. These remarks apply to strictly local attractions, such asare caused by fairly small masses of iron at close quarters. Insome countries, such as South Africa, the whole ground is full ofmagnetic rocks, and the compass is practically useless. The compass sketch. The principle is exactly the same as in triangulating withthe theodolite. A base is measured, and a framework oftriangles is observed. The principal difference is, that theangles of the triangles are not determined as such, but asthe differences between the observed magnetic bearings of therespective sides. Each side of a triangle is drawn as a linemaking a certain observed angle with the magnetic meridian,and is subject to the errors which are inseparable from thesedeterminations of magnetic bear
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectsurveying, bookyear19
