Surveying and Levelling Instruments, Theoretically and Practically Described. For construction, qualities, selection, preservation, adjustments, and uses; with other apparatus and appliances used by civil engineers and surveyors in the field.

CHAPTER III.

Chapter 333 wordsPublic domain

THE MAGNETIC COMPASS AS A PART OF A SURVEYING INSTRUMENT OR SEPARATELY:--Broad and Edge-bar Needles--Manufacture of the Needle--Magnetisation--Suspension--Dip and Adjustment--Lifting-- Inclination--Declination--Variation--Correction--Compass-Boxes-- Description of Compasses--Ring Compasses--Trough Compasses-- Prismatic Compasses--Stand--Surveying with Compass--Pocket Compasses 59