Early Period English Nautical Back Sight Octant by J. Ramsden

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Early Period English Nautical Back Sight Octant by J. Ramsden

About the Item

Presented is a mariner's octant made during the first half of the 18th Century. It is fitted with two horizon mirrors and two peep sights, the lower set being for taking back sights. It has the highly desirable imprint of a partial anchor with initials on either side on the arc between 45°; and 50° which is known to be that of Jessie Ramsden, one of England's foremost instrument makers. Jesse Ramsden invented the dividing machine allowing for the precision marking of degrees on an instrument's arc in 1775 and also made these arcs for others. The accuracy and sharpness of the arc's numerals suggest that this instrument was made by an advanced instrument maker, one who would stand at the top of his trade. 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 of his own manufacture, 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. This octant is marked J.B. Le Roy on the crossbar with the name listed in Webster's Database of Instrument makers with only one example dating to 1820. The instrument is 13 3/4 inches on the vertical which is still oversize for octants, but smaller than the typical Hadley style octant of 17. It was Hadley that invented the "double reflecting" principal introducing it to the Royal Society in London in 1731. It is in its natural state with a mellow patina of age that has developed over the last 216 years and is remarkably well preserved considering age and use at sea. Please read the Condition Statement for details. MARKINGS: You can clearly see the flukes of an anchor between 45 and 50 degree position on the arc. With the aid of a loupe you can make out an initial on either side of the anchor. The metal fittings are precisely machined, and makes this instrument a work of engineering excellence for so early a period. Inside the case are eight notations in pencil which solve Local Apparent Noon sights for latitude. In addition is, Bark Sunette, and the name of the master, which is illegible. There is also an H. Duren, 39 Burling Slip, New York, instrument maker's label. Duren was active there in the 1850's, but this octant, made in England, predates that by a wide margin. The case is the early style stair step, keystone design of this period. Both the top and bottom have age cracks, but everything is secure. The inside has an H. Duren, 39 Burling Slip, New York, instrument maker's label pasted over the remnants of a second label. There numerous pencil notations in the inside which are discussed under markings. It is strong and sturdy, and the octant fits as it should. There are a number of different coats of paint in Colonial greens. There is a lock, but no no key.

Materials and Techniques:
Brass,Ebony,Ivory
Place of Origin:
England
Period:
18th Century and Earlier
Date of Manufacture:
Late 18th Century
Condition:
The instrument is in excellent condition. The graduated arc, and all its hardware are in working order. All three bronze legs are original. It is missing the original ivory pencil on the cross bar as are most instruments of this age. All three mirrors have most of their silvering, but show their age. The machinery is all present. Copyright 2012 Land and Sea Collection. All Rights Reserved.
Seller Location:
Palm City, FL
Reference Number:
1stDibs: U120217925725