Presented is a very large octant with an index arm of 16 inches made by the famous British instrument maker, Spencer, Browning & Rust of London. It is only one inch smaller than Hadley's “double reflecting” octant which was submitted to the Royal Society in London in 1731. Shortly thereafter, Hadley began selling octants with a vertical dimension of 17 inches compared to this instruments 16 inches. We can conclude that SBR was one of the first to adopt the Double Reflecting principal in their own instruments.

Housed in a keystone, stair step case of the period

It has the characteristics of a very early octant consisting of:

An early style Ebony frame

Three mirrors

Two peep sights

Maker's name on cross member

Ivory pencil holder and ivory tab on back

Flat brass index arm 16 inches or longer

Graduated arc from - 5 degrees to + 100 degrees

Vernier reading from right to left, 0 to 20 minutes

Precisely 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 precise spacing and markings on the arc suggest that this instrument was made by a superior instrument maker, standing at the top of his trade. In our opinion, it is the equal in quality of any instrument of this early period.

MARKINGS:  In addition to the cross member having the maker's name, at the center of the ivory degree's scale, between 45 and 50 degrees, is inscribed in script "SBR" identifying this instrument as that of Spencer, Browning & Rust, of London.

Maker's name on cross piece

SBR intitals between 45° & 50°

Spencer Browning Rust worked in London from 1724 to 1840 when the name was changed to Spencer Browning & Co. after the death of Ebenezer Rust.  The successor, Spencer Browning had offices at a number of addresses on Wapping High Street, London and were in business until 1870. They had an early dividing machine and inscribed arcs for others. Ref: Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1995), p. 261.

Machinery looking towards index mirror  Looking toward horizon & back sight mirror The metal fittings are precisely machined, which makes 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 1/8 " wide Index mirror 49 x 34 mm Horizon mirror - 24 x 20 mm Back sight mirror - 24 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 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 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 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.    Old style vernier reading right to left      Viewing horizon & back sight mirrors CONDITION: The instrument is in good condition except for some minor faults. The front machinery of the octant was polished some time ago and has since developed some age patina. On the back, some of the machinery is polished and some isn't. The graduated arc is excellent, and all the hardware are present. All three bronze legs are original. It has the ivory pad on back, and the original small ivory scribe. The three mirrors all have remnants of silvering, but show their age.  The Case is  the typical stair step of this period. We believe it not to be original to this octant being made of Pine rarther than Mahogany. The corks are recent replacements. The top has a long age crack in the lower panel and some chips are missing along the front edge. It also is slightly warped and does not register exactly when closed. The bottom has a smaller age crack and shows normal signs of age. Otherwise it is strong and sturdy, and the octant fits as it should. There is no lock, but there two period hooks and eyes.                          Period style stair step case. Note the age crack to the right 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 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, Indonesia, Ireland, Israel, Italy, Japan, Kuwait, Latvia, Luxembourg, Malaysia, Martinique, Mexico, New Zealand, Nigeria, 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.   Buy this very special early Spencer, Browning & Rust octant! It is a perfect find for your collection or a special gift. Copyright 2010 by Land And Sea Collection™, All Rights Reserved