made in England

Contact goniometer

A contact goniometer is a device for measuring the inter-facial angles of crystals. (Crystals of the same material always have the same angles between crystal faces.) This English example was made in the early 19th century.

The instrument (pictured in its leather case) consists of a brass protractor with adjustable steel arms to fit the angle between crystal faces, held together by a screw. The base of the protractor is signed 'Cary, London'.

French crystallographer, Rene Just Haiiy (1743-1822) proposed that the external appearance of the crystal's facets was a reflection of its internal structure. He used a contact goniometer of this type.

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Online ID:	000-100-102-731-C
Image Rights Holder:	National Museums Scotland
Project:	0098: National Museums Scotland Project description \| View all records in project
Ref:	National Museums Scotland T.1975.42 C
Date:	Early 19th century Early 19th century Early 19th century
Material:	Brass. Inscription: Cary London Brass. Inscription: Cary London Red leather
Dimensions:	42 mm R 85 mm L
What:	Case, goniometer Goniometer arm Protractor, goniometer
Subject:	19. MATHEMATICS (Departmental Classification) 19. MATHEMATICS (Departmental Classification) 19. MATHEMATICS (Departmental Classification)
Who:	Cary (Inscribed on the goniometer) Cary (Inscribed on the goniometer) Cary, London (Maker) Cary, London (Maker) Cary, London (Maker)
Where:	England, London England, London England, London England, London England, London
Event:
Description:	Protractor from a goniometer, signed 'Cary, London', early 19th century Two adjustable arms from a goniometer, England, early 19th century Leather case for a goniometer, England, early 19th century
References:	For Cary, see Clifton, Gloria, Directory of British Scientific Instrument Makers 1550-1851. London: 1995, pp 50-1 Tutton, A. E., Cystallography and Practical Crystal Measurement. London: 1911, p 24
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