A Manual for Practical Surveyors

adjusted angles of deflection angular point applied attached attraction bearing beginning calculations centre chains closing line column correction correctly course determine difference direction distance divided equal error Example feet former given gives ground hand horizontal instrument laid land length line A B lower plate magnetic manner marks means measure method minutes move nearly needle object observation obstacles obtain offset opposite parallel perches perpendicular plate position practice preceding present bearing prolong PROPOSITION random line remove reverse right angles right line rule run a line run the line screw side staff stake subtracted sufficiently sure survey surveyor taken tance tang tangents tion transit triangle tripod true line variation vernier