GIANT THREE MIRROR PRESENTATION BACK SIGHT OCTANT HADLEY STYLE Ca 1770    Unusual Gold Gilt Machinery & Brass Covered Index Display Stand Included! Presented is the largest octant with an index arm 17 1/2 inches long, which makes it one of the largest instruments of this type known. It has other interesting features which sets it apart from most other Hadley type octants, which include: Wood index arm 22% in-cased in brass, Mahogany frame All the metal work gilted in gold. Unusual vernier with a center index graduated 5 to 10" to right and 15 to 10" to left It is one half inch larger than Hadley's “double reflecting” octant which he submitted to the Royal Society in London in 1731. Shortly thereafter, Hadley began making octants with a vertical dimension of 17 inches. There is no case. There is only a single octant with these features and this size out of numerous included in the epic book, "Sextants at Greenwich", by W.F. J.  Morzer Bruyns which catalogs the collection of antique navigation instruments at England's National Maritime Museum. It appears on page 112 under accession number 042 NAV 1306 and was made by Goater, Wappin, London in about 1769. For a photograph of one very similar to this one, see page 46 of Peter Ifland's wonderful book, "Taking the Stars".  A single similar octant is in "Sextants At Greenwich"  Compared below to an octant of of the same Ca 1795 period with an arc by the famous English iinstrument maker, Jessie Ramsden. Ramsden was the inventor of the dividing machine which made accurate instruments of smaller size possible. An octant by Ramsden Ca 1795 with near 14 inch index arm to the left It's rare gold gilding, very large size and high quality, make us believe that it was made for presentation. And the remarkable condition of its ivory, and overall condition would indicate it was preserved in near original condition in a cabinet.         Shown on display stand which is included Other features that are characteristic of an early octant consist of: An early style Mahogany frame Three mirrors Two peep sights Ivory pencil holder with lead pencil and ivory note tab on back Flat index arm 16 inches or longer Graduated arc from - 5 degrees to + 95 degrees Vernier reading from right to left  Machined bronze fittings Single set of three movable shades (filters) 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". The ivory scale is precisely marked with large size numerals and sharply engraved marks on the arc. The ivory shows little age degradation or discoloring which suggests the instrument was stored away from daylight. This further supports our conclusion that it was made as a presentation piece and has seen little use. It clearly was made by an experienced instrument maker standing at the top of his trade. MARKINGS:  No maker's mark present  Machinery  looking towards index mirror  Looking toward horizon & back sight mirror PROVENANCE: Purchased at auction from top tier house. Prior ownership a respectable collector who carefully collected and bought and sold throughout the years. Looking towards Horizon mirror & Back sight Looking toward Index & Horizon mirror The metal fittings are precisely machined, which makes this instrument a work of manufacturing excellence for this early a period. SPECIFICATIONS: Arc reads - 5 to +95 degrees Length of index arm 17 1/2" long Radius of index arm 15 3/4" Width of frame at arc 15" wide Index mirror 47 x 36 mm Horizon mirror - 22 x 20 mm Back sight mirror - 22 x 20 mm Three movable shade glasses Two Peep sights Weight 2 Lbs 12 oz DATING THE INSTRUMENT: The arc measures from - 5 to plus 95 degrees on a Mahogany frame. It is known that Mahogany went out of use in favor of Ebony some time after 1750. The octant has a flat wood index arm, partially encased in brass, that measures 17 1/2 inches long to the clamp. 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 the center to the right and to the left in 5 second increments up and down. Two hole peep sight with "flap", and a movable three sun shades cluster serve both horizon mirrors. All of these features date the instrument after 1750 and before 1780, likely Ca 1770. 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.   Special style vernier reading from the center Unusual gilded brass portion of index arm CONDITION: The instrument is in fine overall condition except for some minor items which are mentioned out of a sense of thoroughness. The gold gilting is worn in places which is a natural result of the aging process and less so than the similar octant at Greenwhich. Approximately 95% of the gilt remains. There is a small chip of wood missing at the lower left leg and there is a small chip of wood missing on the back of the upper slot for the mirrors. The ivory arc is 3/32" smaller than the groove. The wood frame is not evenly smooth in a couple of places. The lower peep sight is slightly different, and the upper turned brass leg is longer and smaller in diameter than the others. Both are likely old replacements. Some of the screw heads have irregular slots showing use. The mirrors have the normal loss of silver and degradation of age, but are in better condition then would be expected after 232 years.  The graduated ivory arc and vernier are in excellent condition, and all the hardware is present. It has the ivory pad on back, and the original small ivory scribe with lead. There is no case.                           Back of octant showing all gilded brass machinery A very rare, and special example of an early Hadley style octant of Giant size and having special gold gilding! 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, 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 Upon Oceans, 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 five 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 within the continental United States if the error is due to our fault. International buyers welcome, but inquire first. We have satisfied customers in Argentina, Australia, Austria, Belgium, Bermuda, British Virgin Islands, Canada, Chile, Republic of China, Czech Republic, Democratic Republic of Congo, Denmark, Estonia, England, France, Germany, Greece, Holland, Hong Kong, Hungary, Iceland, Indonesia, Ireland, Israel, Italy, Japan, Kuwait, Latvia, Luxembourg, Malaysia, Martinique, Mexico, New Zealand, Nigeria, Norway, Nova Scotia, Panama, Philippines, Poland, Portugal, Puerto Rico, Romania, Russia, Saudi Arabia, Scotland, Singapore, South Africa, Spain, St. Maarten, Sweden, Switzerland, Thailand, Turkey, United Arab Emirates, USVI and the Eastern Caribbean.   ACCEPTED FORMS OF PAYMENT are Bank wire transfer, cashier's check, or personal check in which case the item will be held until cleared. Our prices are quoted net to seller, but credit cards may be accepted through PayPal for verified members by special arrangement. This very special early octant is a perfect find for your collection or a special gift for someone of importance. Copyright 2012 by Land And Sea Collection™, All Rights Reserved