Subterraneous Surveying: With and Without the Magnetic Needle

6th column 80 links ABCD acre angle formed bearing and distance Bearing Lengths bearing of F Bord holed centre chains of easting chains of northing Chns circumferentor commencing D. K. CLARK degrees contained direction drift easting or westing error EXAMPLE Fix the instrument following bearings following subterraneous survey form a bearing form an angle fourth bearing headways horizontal distance instrument whose needle let the bearing magnetic needle magnetic variation magnitude meri meridian line meridian NS meridian of 23 needle has 23 number of degrees number of tons plan's meridian plotted PREPARATORY TABLE protractor remove the instrument S. E. or W. N. seam second bearing shaft side south magnetic meridian south meridian subterraneous excavation Suppose the bearing surface survey-book take the bearing tance theodolite theorem traverse tables true meridian variation ns W 8 chains W. N. or S. E. west variation wish to know