Wooden Gunter's ruler

DateEarly 19th century

Object number00051676

NameRuler

MediumWood

DimensionsOverall: 154 x 35 x 3 mm, 9 g

ClassificationsTools and equipment

Credit LineANMM Collection

Terms

DescriptionA wooden Gunter's Ruler, also known as a 'Gunter'. This ruler 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. HistoryThis non-sliding logarithmic scale, known as a Gunter rule, was produced by Edmund Gunter shortly after the method of logarithms was publicly released by John Napier in 1614. Gunter’s rule, in its simpliest form, had the "numbers from 1 through 100 laid out as a two-cycle logarithmic scale. Instead of looking up the logarithms in a table, adding them and looking up the result of the multiplication, all you had to do was use a pair of dividers to add the lengths representing the two multiplicands on the NUM scale; the result could be read right off the same scale... Given the speed with which this allows you to calculate, it is small wonder that Gunter’s rule was used well into the 19th century; in fact it was part of the standard equipment kit for ship navigation in the British fleet." The slide rule, later invented by William Oughtred shortly afterward, was pair of Gunter scales juxtaposed to allow adding the lengths without the dividers. The 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.