Liquid compass

Bowl-Black painted brass, filler plug at side, expansion chamber at base of bowl. An electric lamp is also fitted into side of bowl. Verge glass graduated to 360 degs. A large prism azimuth circle is fitted having a fore sight as well as a "V" above the prism. Mounted in black painted brass gimbals 7.25" (18.5cm) dia. which are secured in a V-shaped bracket being secured to its base by a central bolt. Below bracket is a cylindrical corrector magnet carrier.
Card-Diameter:4.3" (11cm) white painted mica (?) with black markings, graduated to 360 degs. and with a second set of mirrored graduations. Sixteen principal points (English markings).