Maps and survey . student should train himself to do all thecalculation mentally, always remembering that the process is atbest only a rough one, and that quantities of a foot or two haveno real significance. Otherwise it would not be legitimate touse the convenient whole number 20 in place of the moreaccurate I9i. The older pattern Service protractor has scales which showthe horizontal distances between contours for each degree ofslope on two different scales. These are not of much use, sinceit is difficult to interpolate for the fractions of degrees. It is farbetter to accustom oneself from
Maps and survey . student should train himself to do all thecalculation mentally, always remembering that the process is atbest only a rough one, and that quantities of a foot or two haveno real significance. Otherwise it would not be legitimate touse the convenient whole number 20 in place of the moreaccurate I9i. The older pattern Service protractor has scales which showthe horizontal distances between contours for each degree ofslope on two different scales. These are not of much use, sinceit is difficult to interpolate for the fractions of degrees. It is farbetter to accustom oneself from the start to work out mentallythe distances in yards, and to take these off the scales of yardsfound on the protractor. Height above ground of the observers eye. In strictness it should be necessary to take account of thefact that the observations are made from a point about five feetabove ground. On short rays one may take sufficient accountof this by observing to some object such as a bush or the top of Plate XV. Plane Table and Sight Rule: School of MilitaryEngineering pattern.
Size: 2065px × 1210px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectsurveying, bookyear19
