Bowl-An enclosed brass cylinder 0.9" (2.3cm) high. It has a chrome flap that covers the square aperture which allows light through. The light passes through the card and the image is reflected up through a hole in centre of box and onto a glass screen. The glass screen has a metal back plate which is movable. The screen and back plate both fold down. Has card stop and locking mechanism on side. In red leather carrying case.
Card- Vertical type, graduated 0-360 by 1/2 degree divisions.
This compass appears to have been designed for use under bright light conditions such as those found in the Polar Regions. The light enters the small window at the front and is reflected, by a prism, through the transparent compass card and onto the glass screen at the top.
Inscribed Grubb's Patent. Sir H. Grubb took out his patent in 1901.