Drift Sight US Navy Mark VII Viscount and altimeter

and altimeter

The indicator receives an electrical signal from the internal radio compass system

The Army Type B-16 Direct Reading Magnetic Compass was used across a number of US Army Air Corps and Air Force aicraft during WWII

The fluid is contained the rear chamber

The ~60 page manual describes the operation and maintenance of the system

Drift Sight US Navy Mark VII Viscount and altimeterThis is a WWII era Drift Sight Mark VII 88 S 900 as used in multi crewed aircraft of the US Navy. A drift sight is used to determine the degree of drift from the intended heading due to cross winds left or right, to permit correction of the course by flight controls. The instrument would either be installed onto an angled periscope installed in the side of the fuselage pointed 90deg to the ground. As the aircraft travels over the earth's surface,