An accurately balanced magnetic needle, strongly magnetised is fitted with hardened steel pivot working in jewels cup bearing. The needle can be easily removed for reversal. The inclination scale is of chrome brass graduated in degrees 0-90 four times. The case is made of nonmagnetic cast alloy, duco painted, has easily removable plate glass window and rotates fully on heavy brass base, its rotation being measured by a brass chrome dial 0-360°. It is fitted with levelling screw and spirit level.