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Title: Circular plotting protractor patented by E.R. Zenthon in 196 [Go to resource]
Description: Circular plotting protractor patented by E.R. Zenthon in 1960, aluminium, 2 ft inner diameter, with 8 aluminium scales and perspex centring sheet in fitted wooden box License: http://creativecommons.org/licenses/by-nc-sa/2.5/ Subjects: drawing instruments
circular protractorsTemporal: 1960-1970 Source: Science Museum Identifier: 1988-9 Go to resource More Like this...
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