Ivory sector

DateEarly 19th century

Object number00051674

NameSector

MediumIvory, brass

DimensionsOverall (closed): 165 x 34 x 4 mm, 34 g
Overall (open): 305 mm

ClassificationsTools and equipment

Credit LineANMM Collection

Terms

DescriptionAn ivory sector with brass hinge at the centre. It features logarithmic scales as well as various other scales to measure angles and distances and can act as a divider. This sector is contained in a flip-top case and part of a set of drawing instruments designed to fit in a pocket or bag. Instruments such as these were common to a range of professions, including engineering, surveying and navigation and were popular in the late 18th and early 19th centuries. HistoryThe use of drawing instruments dates at least to the Classical period and the contruction of large scale public buildings. Instruments such as dividers and scale rules remained little-changed up until the 18th century when advances in science and technology combined to fuel the Industrial revolution. The development of new drawing instruments is closely linked to the rise of new specialist professions such as engineering, surveying and navigation. The refinement of sextant scales by Jesse Ramsden is just one example of a burgeoning refinement in instruments in the late 18th century. Sometimes referred to as 'gentlemen's travelling cases' or 'etui', pocket instrument cases were designed as a convenient accessory. Often covered in sharkskin, fishskin, leather or turtleshell they could contain a small variety of instruments including folding scale rules, protractors and dividers. In contast to the larger range of instruments contained in magazine cases, pocket cases were for essential instruments.SignificanceThis early English pocket drawing set is significant and representative of instruments used by explorers and surveyors during the 19th century. Encased in a fish skin flip-top container, the set is designed as convenient personal equipment for use in the field.