Item 82: John Northcott miscellaneous papers, 1914-1915 - Page 13

[Page 13]

Steps in plane tabling - (1)  Select a base line.

(2)  Measure the base.

(3)  Fix points by intersection.

(4)  Fill in the detail, mainly by Resection.

True North.  (1) Prolong the major axis of the Southern Cross 4½ times in the direction of its tail and the point reached will be within 1º of the South Pole.

(2)  Hold the watch horizontally face upwards, with a line joining the centre & 12 o'clock pointing towards the Sun.  Then the line from the centre of the dial to a point ½ way between the hour hand & XII is approximately North.

True & Magnetic Bearings

[See image for drawings.]