|Physical description||Aluminium, Brass, Glass, Steel|
|Place made||Australia: Queensland, Brisbane, United Kingdom: England, Greater London, London|
|Date made||c 1914-1918|
First World War, 1914-1918
Prismatic compass : Lance Corporal J D Mack, 8 Light Horse Regiment, AIF
Circular, brass, prismatic compass. The disc shaped lid is detachable and can be fitted to the bottom of the compass when not required. There is a hinging brass vane bolted to the outside circumference. Attached to the vane is a broken, vertical, hair line sighting wire. Also bolted to the outside circumference, opposite the vane, is a height adjustable, pivoting brass and prismatic glass viewer which folds over the compass lens allowing the user to see the aiming point and the compass dial simultaneously. A small sliding brass cover protects the prism when not in use. Underneath the glass lens inside the compass, is an aluminium dial, graded in units from one to three hundred and sixty. Every tenth unit is etched with a back to front number. When viewed from the prism the numbers appear the right way around. The aluminium dial is bisected by a flat stainless steel bar with a sliding weight attached and has a central brass mounting bead. The mounting bead sits and spins on a vertical brass spike which is fixed to the body of the compass. Bolted at three points to the underneath of the compass is a circular flange with a female threaded collar which can be used to fit onto a tripod.
This prismatic compass is associated with the military service of 524 Lance Corporal John Dodd Mack. Mack fought at Gallipoli, Sinai, Palestine and Syria during the First World War. He was born at Lismore in New South Wales and was educated at Geelong College, Victoria. He worked as a Manager at Berry Bank Station in Victoria before enlisting with the 8th Light Horse Regiment, AIF, on 6 January 1915. On 22 April 1917 he was accepted as a member of the 3rd Light Horse Brigade scouts and served with them for the duration of the war and later in March 1919 during the Egyptian rebellion. He was promoted to Lance Corporal on 3 December 1917 and was wounded in action at Es Salt in Palestine on 3 May 1918. He returned to Australia aboard the troopship 'Dorset' on 11 June 1919 and was discharged from the AIF on 11 August 1919.