Elliott Bros late 19th century optical square in fitted case
This late 19th century instrument is called an optical square or a right angle prism, it's purpose being to facilitate the layout of a grid pattern, by enabling one to see lines to the left or right which are 90 degrees to the line of sight being viewed through the pinhole viewer. Engraved on the brass drum'ELLIOTT BROS LONDON' a partnership between Frederick Henry and Charles Alfred Elliott, formed in 1853 after the death of their father William Elliott. In good working order and measuring 47mm in diameter by 17mm in depth, it's a well made instrument, and comes with its original silk and velvet lined outer case, emblazoned'ELLIOTT BROS LONDON' on the silk lid lining. Please study the photos as they are part of the description, and I will be happy to answer any questions if I can.
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