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Douglas Reflecting Protractor
[Text discription below.]
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40017
A Rare Douglas Reflecting Protractor:
English ca. 1811-1825. Signed Cary London and "Patent 132." This was William Cary (w 1789, p 1891), the partnership of William and John "1" Cary (1791-1816) , or the partnership of George and John "2" Cary (1821-1851). The Cary's were scientific instrument makers working at various addresses in the Strand, London; i.e. 181, 182, 272, and 277. They also occupied premises at 86 St. James and Fleet Street in London. The name Cary was carried on posthumously after William Cary's death, by his decendants, and is found on instruments until 1891. The term "Patent 132" is a misnomer and should correctly be understood in two parts: "Patent" meaning the design of the instrument was patented, and "132" simply refering to the serial number. No instruments with identical numbers are known, and some are recorded to be as high as 216.
This intriguing instrument is constructed as a combination of a sextant with vernier, protractor, and scale rule. The sextant is set atop the protractor and scale rule. The sextant has no shades. Unlike a normal sextant, there is no tangent or clamping screw. Instead, tension is adjusted at the pivot axis, and is very tight, precluding any drift of the observed readings. The index mirror is mounted on an arm that moves along the protractor and carries the vernier. The horizon glass and the sighting vane are mounted at opposite ends of a slotted index arm. The slot of this index arm rides over a pin that is fixed to the arm of the index mirror. The index and horizon glasses are attached to the substructure by screws. The index glass is fixed, but the horizon glass is movable by set screws for calibration. Movement of the instrument provides readings along the protractor's arc from 0° to 130°, graduated to 30 minutes, but is only usable in practice from 0° to 120.5°. The vernier has a scale of 0-30 subdivided into units of 1 arcminute.
The straight limb has a scale marked from 0-1760, and is subdivided on the beveled section into tenths. It also carries a diagonal interpolation scale to 1 yard. Interestingly, this scale is not in metric units or degrees, but in English yards.
Historical:
This instrument was invented by Sir Howard Douglas (1776-1861). Douglas, a noted British military officer and author, received a British patent (#3461) for this "reflecting circle or semicircle" in 1811 for land and marine surveying, whereby the measured angle may be protracted in actual magnitude without reading off. He studied navigation as an army officer shortly before he designed this instrument. Quite ostensibly, the instrument was well received by the scientific community since he was elected a fellow of the Royal Society in 1816 because of it. William Cary, who made the first examples of this instrument, noted that it combined a protractor with a reflecting system as used in a sextant. He also noted that it was "particularly useful in military survey, where the true situations of objects can at once be determined, and the sketch corrected at the same time that it is taken." Instruments of this sort were still available at the end of the century. The signature on this example most likely refers to William Cary Sr.
Condition:
The condition is very fine throughout and nicely preserved within its original case. Lock and key are present. Fully functional.
Sir Howard Douglas:
DOUGLAS, SIR HOWARD, Bart. (1776-1861), British general, younger son of Admiral Sir Charles Douglas, was born at Gosport in 1776, and entered the Royal Military Academy in 1790. He was commissioned second lieutenant in the Royal Artillery in 1794, becoming first lieutenant a few months later. In 1795 he was shipwrecked while in charge of a draft for Canada, and lived with his men for a whole winter on the Labrador coast. Soon after his return to England in 1799 he was made a captainlieutenant, (??) and in the same year he married. In his regimental service during the next few years, he was attached to all branches of the artillery in succession, becoming captain in 1804, after which he was placed on half-pay to serve at the Royal Military College. Douglas was at this time (1804) appointed to a majority in the York Rangers, a corps immediately afterwards reduced, and he remained on the roll of its officers until promoted major-general. The senior department of the R.M.C. at High Wycombe, of which he was in charge, was the forerunner of the Staff College. Douglas, since 1806 a brevet lieutenant-colonel, served in 1808-1809 in the Peninsula and was present at Corunna, after which he took part in the Walcheren expedition. In 1809 he succeeded to the baronetcy on the death of’ his half-brother, Vice-admiral Sir liam William Henry Douglas. In 1812 he was employed in special missions in the north of Spain, and took part in numerous minor operations in this region, but he was soon recalled, the home government deeming his services indispensable to the Royal Military College. He became brevet colonel in 1814 and C.B. in. 1815. In 1816 appeared his Essay on the Principles and Construction of Military Bridges (subsequent editions 1832, 1853); in. 1819, Observations on the Motives, Errors and Tendency of M. Carnot’s System of Defence, and in the following year his Treatise on Naval Gunnery (of which numerous editions and translations appeared up to the general introduction of rifled ordnance). In 1821 he was promoted major-general. Douglas’s criticisms of Carnot led to an important experiment being carried out at Woolwich in 1822, and his Naval Gunnery became a standard text-book, and indeed first drew attention to the subject of which it treated. From 1823 to 183I Sir Howard Douglas was governor of New Brunswick, and, while there, he had to deal with the Maine boundary dispute of 1828. He also founded Fredericton College, of which he was the first chancellor. On his return to Europe he was employed in various missions, and he published about this time Naval Evolutions, a controversial work dealing with the question of “breaking the line “(London, 1832).
From 1835 to 1840 Douglas, now a G.C.M.G., was lord high commissioner of the lonian Islands, where, amongst other reforms, he introduced a new code of laws. In 1837 he became a lieutenant general, in 1840 a K.C.B., in 1841 ,a civil G.C.B., and in 1851 a general. From 1842 to 1847 Douglas sat in parliament, where he took a prominent part in. debates on military and naval matters and on the corn laws. He was frequently consulted on important military questions. His later works included Observations on the Modern System of Fortification, &c. (London, 1859), and Naval Warfare Under Steam (London, 1858 and 1860). He died on the 9th of November 1861 at Tunbridge Wells. Sir Howard Douglas was a F.R.S., one of the founders of the R.G.S., and an honorary D.C.L. of Oxford University. Shortly before his death he declined the offer of a military G.C.B. Bibliography: 1. Fullom, S.W. (1862) Life of Sir Howard Douglas, London & Gentleman's Magazine, 3rd series, xii. p. 90-92. 2. Cary, William (1811) Philosophocal Magazine, Vol 38, p. 186-187, & plate VI. 3. Dictionary of National Biography, Vol 5, p. 1203-1206 for the entry on Howard Douglas. 4. There is an identical Reflecting Protractor in the National Maritime Museum (ID # NAV0140; Serial No. 34 ) with attributes to William Cary ca. 1811. Please see: [rmg.co.uk/collections/objects/rmgc-object-42352]. 5. The National Portrait Gallery: [www.npg.org.uk]. 6. Clifton, Gloria (1995) Directory of British Scientific Instrument Makers 1550-1851. ISBN [0 302 00634 6] p. 50-51.
From 1835 to 1840 Douglas, now a G.C.M.G., was lord high commissioner of the lonian Islands, where, amongst other reforms, he introduced a new code of laws. In 1837 he became a lieutenant general, in 1840 a K.C.B., in 1841 ,a civil G.C.B., and in 1851 a general. From 1842 to 1847 Douglas sat in parliament, where he took a prominent part in. debates on military and naval matters and on the corn laws. He was frequently consulted on important military questions. His later works included Observations on the Modern System of Fortification, &c. (London, 1859), and Naval Warfare Under Steam (London, 1858 and 1860). He died on the 9th of November 1861 at Tunbridge Wells. Sir Howard Douglas was a F.R.S., one of the founders of the R.G.S., and an honorary D.C.L. of Oxford University. Shortly before his death he declined the offer of a military G.C.B. Bibliography: 1. Fullom, S.W. (1862) Life of Sir Howard Douglas, London & Gentleman's Magazine, 3rd series, xii. p. 90-92. 2. Cary, William (1811) Philosophocal Magazine, Vol 38, p. 186-187, & plate VI. 3. Dictionary of National Biography, Vol 5, p. 1203-1206 for the entry on Howard Douglas. 4. There is an identical Reflecting Protractor in the National Maritime Museum (ID # NAV0140; Serial No. 34 ) with attributes to William Cary ca. 1811. Please see: [rmg.co.uk/collections/objects/rmgc-object-42352]. 5. The National Portrait Gallery: [www.npg.org.uk]. 6. Clifton, Gloria (1995) Directory of British Scientific Instrument Makers 1550-1851. ISBN [0 302 00634 6] p. 50-51.
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