PRESENTED is a superior quality late 18th C. mariner's three mirror octant with ebony frame. ivory graduated arc and vernier, and bronze fittings. We can say this instrument is of museum quality without reservation. The arc measures from - 5 to plus 95 degrees. In 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. But over it is the mark of a fouled anchor which belonged to one of Britain's most famous instrument maker's Jesse Ramsden. Among other things, Ramsden was the first to invent a dividing machine which enabled much more precise divisions. He was given a generous 615 pound award by the Board of Longitude for this invention which required that he make the results available to ten other instrument makers for a fee.

 

PROVENANCE: The octant was handed down in the family of the Captain Benjamin Walker of South Eastham, MA. Benjamin Walker's DOB and DOD are unknown. He was one of teh original six settlers of Eastham. It was given by him to his son John Walker, ( 1857-1948), and then by him to the grand daughter of his older brother. John Walker was buried in Winthrop, ME. A note to this effect accompanies the instrument.

 

 

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.

 

THE INSTRUMENT: This beautifully made octant has a brass index arm without a brace that measures 14 inches long counting the tab, which is less than normal for this period. This is a result of Ramsden's advanced method of dividing the arc which allowed for the reduced size. The top horizon mirror is mounted on an adjustable turntable. The base can be rotated by adjustment screws on the back side. The lower mirror adjusts the same way and has a second peep sight. The lower unit is used for taking back sights, and were only fitted to very early octants.

 

Note the early form ivory vernier scale, reading from right to left from 0 to 20 arc minutes, a two hole peep sight with "flap" for the horizon mirror plus a single peep sight for the backsight mirror, and the moveable three sun shades which serve both mirrors on the frame. There is no tangent screw on early instruments only a clamp. All of these features date the instrument before the turn of the 19th century, likely Ca 1777 since Ramsden's dividing machine was invented in 1775.

Early style stair step keystone case interior

INSTRUMENT CONDITION: The sextant appears in its last used condition having been maintained by mariners who too excellent care of it. The index mirror is in much better condition than might be expected with little loss of silvering. age. The horizon mirror has lost much of its silvering, but is in otherwise good condition. The ivory is in perfect condition, except for some age darkening at the ends. The engraving is sharp and distinct. The index arm clamp is complete. The shade glasses are complete. Everything is in good working order. The entire instrument and ebony frame shows as near new. The instrument has all its original machinery. The only thing that has been lost over the years is the ivory pencil holder that has been replaced by  a wood facsimile.

THE CASE: The stepped "keystone" solid Oak case is in excellent condition, but has some age cracks top and bottom. It has its original New England colonial blue coloring. There is no lock or key, but there is a cover plate.

 

Maker's name

Jesse Ramsden's anchor imprint at 55 degrees

The machinery. Back sight to right

Peep sight & horizon mirror

THE LABELS: The large label with the colonial blue wash over is mostly illegible. What can be seen is that it belongs to a mathematical instrument maker with a Boston address. The last name was Dutom or Duton which is not listed in any of the traditional references.

 

The smaller label is that of Fredrick W. Lincoln, Jr. who was the grandson of Paul Revere. Lincoln was born in Boston on February 17, 1817, a grandson of Paul Revere, and became mayor of Boston during the Civil War. He began business under his name as a nautical instrument maker in 1839. In 1858, Lincoln's apprentice, Charles Hutchinson became a partner and the firm name was changed to F. W. Lincoln, Jr. & Co. Hutchinson bought out the business in 1883. Therefore, this octant was either serviced by the Lincoln firm or resold by them sometime between 1839 and 1858.

 

The smaller label was originally pasted over the larger label and the four dots of glue can be seen in the corners. It was lying loose when the instrument was received with corresponding glue residue on its backside.

DIMENSIONS: 

• Arc reads - 5 to +95 degrees
• Length of frame 14" 
• Width of frame at arc 11" wide
• Index mirror 48 x 35 mm
• Horizon mirror -
• Back sight Mirror 22 x 22 mm
• Three shade glasses
• Two Peep sights
• Weight    2 Lbs 8 oz octant   4 lbs 8 oz total

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 a retired Master Mariner, and held a U.S. Navy "D" Qualification as a Senior Skipper - Oceans. For six years he was a Varsity Offshore Coach at the U.S. Naval Academy.

 

OUR UNCONDITIONAL GUARANTEE: If not completely satisfied with your purchase it may be returned, if without damage, within three days of receipt in its original condition and packaging. Returns must be insured for their full value. All that is required is a prior email authorization by us for the return. Unfortunately, no refund can be made for the cost of shipping, packaging and handling unless we are at fault.