A cased a plane table transit alidade level by E R Watts, circa 1945.

Case dimensions: Width: 44 cm. Depth: 22 cm. Height: 14 cm.

E. R. Watts and Son Limited. 123 Camberwell Road, London. Established 1856, traded up to the 1920s as E.R. Watts & Son, with E. R. Watts & Son Ltd amalgamating with Adam Hilger Ltd to form Hilger & Watts in 1948.