This type of folding arm protractor was praised by W. F. Stanley as "the most pefect instrument for accurate plotting." There is no maker's name on either the case or the instrument itself. Nevertheless, there is one which looks exactly like this one in the collection of the Powerhouse Museum, Sydney, Australia. It was made by Edward Esdaile, Sydney, New South Wales, 1919-1941, and had been used at Sydney Observatory, Australia, from 1919 to 1958.
