Scientific Instrument Society 25th Anniversary Exhibition
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41 Early Gunter's Scale
The Gunter’s Scale was mainly used in navigational calculations. I consider this two-foot, boxwood ruler to be the earliest known, dated example.
In 1623 Edmund Gunter (1581-1626) described his mariners cross staff and had a logarithmic ‘line of numbers’ marked on the staff. This evolved into the ubiquitous Gunter’s Scale, which continued to be made, with very little change, until the beginning of the nineteenth century.
It is marked with Lea (Leagues), Rum (Rhumbs), Lon (Line of Longitude), Cho[rds], SR (Sines of the Rhumbs), TR (Tangents of the Rhumbs), Numb (Numbers, a logarithmic line), Sine, Tan[gent], Merid (Meridian-Line), EP (equal parts) and a scale of English inches. These scales were used with a pair of dividers to solve problems in navigation and trigonometry. It is stamped with what is probably the owner’s name, ‘Thomas Annand’ and the date ‘1683’.
See: E. Gunter, Description and use of the Sector, Cross-staff and other Instruments, 1623.
(Note: although both instruments are illustrated, only the cross-staff is graduated with a logarithmic line).
Collection: Peter Delehar, London
Objects lent by Peter Delehar, London:
08. Circular Slide Rule on a Snuff Box, by Hoyau, Paris, 1816
11. Reversible Circular Slide Rule, English, c.1840
25. Slide Rules - a Selection of the Original Pocket Calculators
26. Javal's Ophthalmic Slide Rule, by A. Cretes, Paris, c. 1875
27. Triangular Slide Rule with Four Sliders, by Elliott, London, c. 1870
28. Oil Calculation Slide Rule Designed by Forrest M. Towl, New York, c. 1889
29. Master Rule and Gauging Slide Rule, by Dring & Fage, London, 19th Century
30. Anderson Celluloid Gridiron Slide Rule, by Casella & Co, London, c. 1903
31. Slide Rule in a Drawing Scale, by J. Casartelli, Manchester, c. 1870
32. Circular Slide Rule, by Joseph Lamb, London, c. 1827
33. Roubicek Circular Slide Rule for Surveying, by Neuhöfer & Sohn, Vienna, c. 1870
34. Annular Slide Rule, by Elliott Brothers, London, c. 1875
36. Box Sextant with Integral Slide Rule, by Troughton & Simms, London, c. 1870