And, by the way, why in Heaven's name 'a prismatic compass'?
"The Riddle of the Sands" by Erskine Childers
One prismatic compass, three and a-half inch, with silver ring: 5 pounds 5 shillings.
"Successful Exploration Through the Interior of Australia" by William John Wills
The trouble was overcome by building snow-mounds and taking back-angles to them with the prismatic compass.
"The Home of the Blizzard" by Douglas Mawson
Shoes in themselves are not enough to hang a man, but a prismatic compass assuredly is.
"The Story of the Guides" by G. J. Younghusband
We were travelling entirely by prismatic compass.
"Across Unknown South America" by Arnold Henry Savage Landor
Officers carried revolvers, field glasses, prismatic compass, and various other extras.
"The 28th: A Record of War Service in the Australian Imperial Force, 1915-19, Vol. I" by Herbert Brayley Collett
Meanwhile, Tatum had been reading a round of angles with the prismatic compass.
"The Ascent of Denali (Mount McKinley)" by Hudson Stuck
The top of the easy passage bears by prismatic compass 23 deg.
"Climbing in The British Isles. Vol. 1 - England" by W. P. Haskett Smith
The climbers carried "Magnapole" compasses with luminous points, and sometimes a Mark VIII prismatic; these all worked well.
"Mount Everest the Reconnaissance, 1921" by Charles Kenneth Howard-Bury