Lord Kelvin's Azimuth Mirror and dovetailed wooden storage carrying case. Made by Kelvin, Bottomly & Baird Ltd for Marine Instruments Ltd. Circa 1910-30s. Made in Great Britain. An azimuth circle is a navigation instrument in the form of a brass ring with sights that attaches to the top of a compass to enable the user to take accurate bearings on the sun and terrestrial objects. Dimensions: Case - 12" x 12" x 6.5" / Mirror - 10.5" x 5.5" (Width x Depth x Height)