Watson Bros. 4 Pall Mall, London
Polarizing microscope (lacquered brass) with original accessories in fitted mahogany case. First made 1879 in London by Thomas William Watson (son-in-law of William Tranter, gunsmith of Birmingham). Designed in collaboration with the renowned geologist Frank Rutley. Probably one of the earliest professional quality polarizing instruments made in England. Thomas was joined in business by his brother about 1885 and the name was changed to Watson Brothers. This example comes from about this time.
The main frame is of the common "Lister limb" design which has been adapted for petrological use. There is a graduated rotating polarizer carried on a swing out carrier. The standard ocular for no-polarized work is replaced by a rotating analyzer also with a graduated scale. Quartz and ¼ wave plates are mounted in brass and fit the slot in the main tube. Also supplied with a small lens to fit over the condenser and a disc of calc-spar to fit over the analyzers for stauroscopic use.
Signed on foot "Watson Bros. 4 Pall Mall, London, 5159"