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THREE MIRROR BACK SIGHT
EARLY HADLEY STYLE OCTANT
Ca 1745 - 1755

The octant's vernier scale reading right to left in 0 to 20 arc minutes, Note the verdigris and the finger clamp    The degraded backsight mirror

The brass fittings are precisely machined, which make this instrument a work of manufacturing excellence for this early a period.
 

DIMENSIONS: 

• Arc reads - 5 to +95 degrees

• Length of index arm 16" long

• Width of frame at arc 13 1/2 " wide

• Index mirror 48 x 30 mm

• Horizon mirror - 24 x 21 mm

• Back sight mirror - 24 x 21 mm

• Three movable shade glasses

• Two Peep sights

• Weight 2 Lbs 11 oz octant and case each. Total  5 lbs. 6 oz
   

DATING THE INSTRUMENT: The arc measures from minus 5 to 95 degrees on the scale. It is inlaid in the mahogany 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 mahogany index arm measuring 16 inches long with a finger 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 right to left from 20 to 0 arc minutes, a two hole peep sight, and movable three sun shades which serve both mirrors on the frame. 

All of these features date the instrument to likely Ca 1774 -1775. Some time after 1780, the index arm clamp was superseded by an adjustable tangent screw, which also helps date this octant. 

Ref. Peter Ifland's comprehensive sextant work, "Taking the Stars". particularly figure 64, page 57.
 

Closed keystone case with stair step image of the Period      The back of the Hadley style octant. Two legs are missing

CONDITION: The instrument is in good condition except for some minor faults.  On the back, some of the machinery has a deep patina of age and some doesn't. The graduated arc is excellent, and all the hardware is present. Missing are all three bronze legs. It has a keystoneivory pad on back, but the original small ivory scribe is missing. The index and primary mirrors are in very good condition considering their age. The backsight mirror has lost most of its silvering. There are two spots of green verdigris on the vernier around the pins holding the scale.

The Case is  the typical stair step, keystone design, of this period.  It has been with the octant for a long time, but the carved out section at the lower right front may indicate it is not the original. There is a missing piece of wood at the bottom of the left front and some  scratches and wear marks, all around, but it is strong and sturdy. With the index arm set to the far right, the octant fits as it should. There is no lock, but there a period hook to hold it closed. 

All in all, a rare, desirable, and special example of an early Hadley style octant by England's early largest instrument maker.

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 Syscratchesoard, 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 Tamayr 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 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 Hebrides (Vanuatu), 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, Vanuatu (New Hebrides) and the Eastern Caribbean.

STANDARD 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. Our prices are quoted net to us so that the use of credit cards or PayPal for lesser value items incur extra charges. Terms on overseas sales may be different. 

This is a very special early Hadley style octant! It is a perfect find for your collection or a special gift.

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