VERY Rare Early 19c TWO-Foot Long Boxwood Gunter’s Rule Antique Navigation Tool

A VERY Rare 19c/earlier 24 Inches/2 feet Long Boxwood Gunter’s Rule. An Antique Navigation Tool invented by. It was used to aid mathematical calculations in navigation till 19c in British fleets before the slide rule was invented. Nice patina with clear lines & numbers in black. Size in mm: 7 x 38 x 610. DO NOT USE THE MEDIUM PARCEL OPTION…. Unless you wish to collect this from me in London free. Has many scales, and one marked “NUM”, which has the numbers from 1 through 100 laid out as a two-cycle logarithmic scale. Instead of using the logarithms in a table, one uses a pair of dividers to add the. Representing the two multiplicands on the NUM scale. There are scales for doing trigonometry, such as those marked SIN, TAN and more specialized scales for navigation at sea. For example, a scale marked ML (Miles of Longitude), giving the length of one degree of longitude at a given latitude; or SR, (Sine of Rhumbs) which is the log of the sine of an angle given in rhumbs – which are the standard compass points (N, NE, E, etc). It has brass plugs at commonly used points to prevent damage to the wood from the points of the dividers. Similar item described in National Maritime Museum, Greenwich, London but not DISPLAYED. For a detailed description of all the scales on the Gunter see the Journal of the Oughtred Society, Vol. Are strongly advised to use. Service or a track &. Please pay within 3 days unless you notify me or your order may be cancelled for wasting time. NB: We strive to keep our customers happy. If relevant, do read. Zodiac Guide to Successful Relationships & Careers.