This Fine Octant Has Been Sold. Corporate Gift. Thank you!   EARLY THREE MIRROR BACK SIGHT OCTANT  JESSE RAMSDEN OCTANT Ca 1755 - 1777   PRESENTED is a last half of the 18th C. mariner's octant with the mark of Jesse Ramsden on the arc. It was Ramsden who invented the dividing machine which allowed for the precision marking of degrees on an instrument's arc in 1775. This instrument is a smaller version of the Hadley octant in which the "double reflecting" principal was introduced by Hadley to the Royal Society in London in 1731. Hadley began selling octants shortly thereafter which had a vertical dimension of 17" or more. The instrument is 15 3/4 inches on the vertical. It has been recently polished and lacquered, and is in a remarkable well preserved condition considering its 234 year age and use at sea. You may read the Condition Statement for details. The cross member, which seems to be original is unmarked. This is not as unusual as many instruments were made to allow the retailer or an owner to imprint their name which frequently was not done MARKINGS: Using a magnifier you can clearly see an anchor between 45 and 50 degree position on the arc. The anchor is the well known mark of Jessie Ramsden, perhaps the most famous of all English instrument makers. It was Ramsden who invented the dividing machine which allowed for the precision indexing of degrees on an instrument's arc. JESSE RAMSDEN, ONE OF ENGLAND'S MOST IMPORTANT INSTRUMENT MAKER'S HISTORY: Jesse Ramsden (1735-1800)   Ramsden was one of the most famous English scientific-instrument makers of the second half of the eighteenth century. In 1775, he invented a semi-automatic dividing machine, capable of marking graduated scales on sextants and other nautical and astronomical instruments for his own instruments and provided the same to other mathematical instrument makers. He developed improvements in the manufacture of sextants, theodolites, barometers, micrometers, and countless other devices. One of the most important instruments built by him is the great astronomical circle of the Palermo Observatory. In 1786, elected fellow of the Royal Society of London and, eight years later, member of the Imperial Academy of Saint Petersburg. In 1795, won the Copley Medal, the highest scientific award of his time: the prize was established in 1736 by the Royal Society, thanks to a bequest from Sir Godfrey Copley. What can be clearly seen is the anchor's stock and flukes and with less clarity, an "F"  to the left of the stock and a "P" to its right.There were many instrument makers whose names began with these letters, but most of them made telescopes, microscopes and chronometers. We could find only one who made octants. Peter Feathers, a Scotsman who operated from High St. and Dock St. in Dundee from 1842 until 1872. In 1873 he took in his son as a partner, but this is way too late to be making such a large octant. Therefore, the most likely maker of the arc is the most obvious, Jessie Ramsden, and the shop that did the assembly of the frame and working parts is lost to history.                        Maker's mark a “F” Anchor “P” between 50° & 45° Marked in pencil in a European hand on the center ebony upright is "J 69 over 18 space 44". The 18 44 is not written as a date.  The evenness of the spacing and markings on the arc suggest that this instrument was made by a superior instrument maker, one who would stand at the top of his trade. It is the equal in quality of any instrument of this early period. It has a early style Ebony frame, flat brass index arm, graduated arc and vernier, and precisely machined bronze fittings. The three shade glass assembly is movable for placement at either the index mirror position or below at the secondary position where the third mirror allows for the taking of "back sights".   For details on how we dated this instrument, see below.                  Old style vernier               Rear peep sight & index mirror The metal fittings are precisely machined, and makes this instrument a work of engineering excellence for so early a period. DATING THE INSTRUMENT: The arc measures from - 5 to plus 95 degrees on a Ebony frame which is in excellent condition. It is known that Mahogany went out of use in favor of Ebony some time after 1750. The octant has a flat brass index arm measuring a long 15 1/2 inches, with a tangent screw. Tangent screws began replacing finger clamps in the last quarter of the 18th Century. The horizon mirror is mounted on an adjustable turntable. Its base can be rotated by loosening a screw which locks the mirror's position. A third mirror is below it for taking back sights and is also adjustable. The ivory vernier scale, reads from right to left from 20 to 0 arc minutes, a two hole peep sight with "flap", and movable three sun shades which serve both mirrors on the frame.   All of these features date the instrument after 1750 and before 1780, likely Ca 1775. Some time after 1780, the index arm clamp was superseded by an adjustable tangent screw, which also helps date this octant. See Peter Ifland's comprehensive sextant work, "Taking the Stars". particularly figure 64, page 57.                  Front peep sight & horizon mirror               Period stair step keystone case          VIEW THE GALLERY BELOW FOR MORE PHOTOGRAPHS CONDITION: The instrument is in good condition except for some minor faults. There are some small age splits on the frame, and the nuts holding the two peep sights are missing. The graduated arc, and all its hardware are in working order, but the index arm becomes stiff at 15 degrees. All three bronze legs are original. It has the ivory pad on back, but the original small ivory scribe is missing. The three mirrors all have remnants of silvering, but show their age. The machinery has recently been polished and lacquered. The Case is  the typical stair step of this period. We believe it not to be original to this octant though the two have been together for almost as long as the octant is old. We reach this conclusion because it is not of the same quality as the instrument, and the wood is unfamiliar. The top has a long age crack from front to back that has been repaired by a piece of sheet copper that is nailed from the inside. The upper piece has a short age crack from side to side. It also is slightly warped and does not register exactly when closed. Otherwise it is strong and sturdy, and the octant fits as it should. There is no lock, but there is a period hook and eye.                          Instrument in case. Note copper repairs to cover All in all, a rare, desirable, and special example of an early Hadley style octant. DIMENSIONS: Arc reads - 5 to +95 degrees Length of index arm 15 3/4" long Width of frame at arc 13 " wide Index mirror 49 x 32 mm Horizon mirror - 24 x 20 mm Back sight mirror - 24 x 20 mm Three movable shade glasses Two Peep sights Weight 2 Lbs 4 oz OUR QUALIFICATIONS: We are one of the few company's still selling navigation instruments that know anything about them. For purposes of judging whether Joel's opinion counts, he was the editor of the chapter on sextants of the 1977 Edition of "Bowditch", The American Practical Navigator, NAVPUB 9; a member of the U.S. Naval Academy Navigation Symposium Board, 1975 -1978; the author of a book on marine sextants, Cornell Maritime Press,1975, and the founding president of Nautech Maritime Corporation which partnered with Tamaya of Japan in the introduction of the MS 733 Spica, the MS 833, Jupiter, MS 933 Venus sextants and the famous NC-2 navigation computer, in the U.S. market. Joel is also a retired Master Mariner, and held a U.S. Navy "D" Qualification as a Senior Skipper - Oceans. From 1995 through 2000, he served as a Varsity Offshore Sailing Team coach at the U.S. Naval Academy.   OUR UNCONDITIONAL NO NONSENSE GUARANTEE: If not completely satisfied with your purchase it may be returned, if without damage, within three days of receipt in its original packaging. Return items must be insured for their full value. Only a prior email authorization by us for the return is required. Shipping charges are  included in this offer if the error is due to our fault. International buyers welcome, but must inquire first. We have satisfied customers in Argentina, Australia, Austria, Belgium, Bermuda, British Virgin Islands, Canada, Chile, China, Czech Republic, Democratic Republic of Congo, Denmark, Estonia, England, France, Germany, Greece, Holland, Hong Kong, Hungary, Iceland, Ireland, Israel, Italy, Japan, Kuwait, Latvia, Malaysia, Martinique, Mexico, New Zealand, Norway, Nova Scotia, Panama, Poland, Portugal, Puerto Rico, Romania, Saudi Arabia, Scotland, Singapore, Spain, Sweden, Switzerland, Thailand, Turkey, United Arab Emirates, USVI and the Eastern Caribbean.   ACCEPTED FORMS OF PAYMENT are Bank wire transfer, cashier's check, money order, or personal check in which case the item will be held until cleared. No credit cards or PayPal accepted on this item. Buy this very special early octant Now! What a great find for that special person who can appreciate it. Copyright 2009 by Land And Sea Collection™, All Rights Reserved Select a thumbnail from the left to zoom. Image #1 Image #2 Image hosting and Zoom Gallery by VillagePhotos.com