Miniature Navigation Outfit, with its Own Horizon Click on any image for a larger view.

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BOX SEXTANT OUTFIT WITH GIMBALLED ARTIFICIAL HORIZON MIRROR, English, c.1820, signed "Simms, London." The 2-3/4" (7 cm) diameter brass sextant is complete with inlaid silver scale and one-arcminute vernier, scale magnifier, geared index arm, mirror adjusting tool, peepsight, single draw telescope, two swing-away filters, and screw-on handle/cover. The cover is engraved with tables of tangents and arctangents. The original fitted mahogany case contains a weighted plane mirror in double gimbal rings, which sets up on folding supports in the case top. This is a novel approach to providing a perfectly horizontal reflecting surface; in use one measures the angular distance from a star, the sun, or even a coastal landmark, to its reflection in the mirror. Half this will be the altitude of the object, determined without reference to the horizon itself, which may be obscured by haze, etc. Condition is very fine throughout. This is one of the few known instruments produced by a member of the Simms family of nautical and mathematical instrument makers. Made prior to William (II)¹s partnership with Edward Troughton beginning in 1826, it is the only example of this unusual design we have come across. (8220) $4500.


Large Early Dividers Click on any image for a larger view.

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EARLY BRASS AND STEEL DIVIDERS, Continental, c. second half 17th century, 9-1/4" (23 cm) overall, rather primitively shaped but with a five-leaf brass hinge. In fine condition complete with an early sheet brass cover for the tips. (8210) $875.


Cary's "Double" Design, plus History, plus Gold! Click on any image for a larger view.

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GOLD SCALE SEXTANT BY CARY, English, c. late 19th century, #3271. This elegant sextant is Cary's "partial double frame" design and has a splendid inset scale of gold, divided every ten arcminutes, with a silver vernier reading to ten arcseconds. The instrument has Reeves' endless tangent screw (an 1882 patent), the governmental broad arrow mark, the Hydrographic Office mark, and the repair mark of Cooke, Troughton & Simms. The scale radius is 8"; the overall height 10-1/2" (27 cm). The sextant is equipped with one telescope, four index filters, two horizon filters, scale magnifier, scale diffuser, index arm spirit level, and fine adjustment for horizon mirror. There is no case. Condition is fine, noting a couple of small dents.

This is a good example of the rigid but lightweight innovative design by the firm founded in the 18th century by William Cary. Special features here include the quick-release index arm clamp coupled with long tangent screw fine motion with precision readout, and the unusual little spirit level on the index arm, useful when the horizon is obscured or elevated. This sextant must have an interesting history, with its governmental service and documented 20th century repair. A very rare example of the top of the line gold scale on a navigational instrument. (9235) $3950.


Handsome Telescope by Ross, for Gieve Click on any image for a larger view.

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FINE ENGLISH SPYGLASS, c. early 20th century, signed ³Ross, London, No. 26235; Made for J. Gieve & Sons, Portsmouth.² Opening from 17-1/2² to 25² (44 - 63 cm) by single drawtube and objective shade, the telescope has nickel-plated brass construction, with stitched leather binding to the main tube. It is complete with achromatic doublet objective, erecting eyepiece system, dust cover and dust slide. Condition is very fine giving fine images. The retailers had premises on High St. in Portsmouth, and are known for naval swords as well. (7246) $750.


Remagnetizing Compass Needles at Sea Click on any image for a larger view.

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A NEAR-MINIATURE LODESTONE, probably Continental, c. early 18th century. Measuring 1-5/8" (4 cm) wide and only 1/2" (12 mm) thick, it is constructed with a somewhat irregular slab of naturally magnetic magnetite stone sandwiched between two iron pole pieces at the ends (to concentrate the magnetic attraction), the whole bound in brass and with a brass suspension. Condition is fine noting some rust to the iron, and one mounting nut lacking. The stone retains slight attractive power.

A lodestone was essential equipment for navigation at sea, being required from time to time to remagnetize the compass needle(s). Its power was considered magical, and its value great. The diminutive size of the present rather attractive example implies use for pocket compasses, small surveying compasses, and sundial compass needles. An uncommon size. (9192) $2600.


Early "Adams-Type" Box Sextant Click on any image for a larger view.

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FLAT DRUM SEXTANT, English, c. first half 19th century, constructed of brass, 4-1/4" (11 cm) in diameter and 1-5/8" (3.6 cm) thick, the interior with "wriggle-work" designs and fine clear lacquer finish, the exterior of chemically darkened brass. A geared index arm carries an internal mirror, and is set with a silver vernier divided to one arc-minute. This reads against the 0° - 122° inset silver scale. There is a scale magnifier on long arm, and separately insertable dark red index and horizon filters. The sextant cover can be screwed onto the opposite side to serve as handgrip, and to avoid loss. The instrument itself is quite handsome, and fully functional, but we note a crack and chips to the cover¹s threads, and some edge damage to the sextant surround. The interior lacquer finish is excellent, the exterior rubbed and worn.

This is an unusual form of pocket "box" sextant, considerably larger in diameter than most, and yet no thicker. It is similar to that described and illustrated in Adams'/Jones' Geometrical and Graphical Essays of the late 18th century (although here with interior rather than exterior rack work). For an Adams example see Tesseract Catalogue 38 Item 55. (9200) $1450.


Fine Measuring Telescope with Divided Objective Click on any image for a larger view.

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A DIMINUTIVE HAND-HELD SPLIT-LENS RANGEFINDING TELESCOPE, French, c. third quarter 19th century, finely signed "Micrometre a vis et a cadran, No. 1, E. Lorieux pere a Paris" and "Lorieux, Passage Dauphine 13, Paris." With an overall length of 7-3/4" (20 cm), extending to 9-1/4" by single drawtube, the telescope has erecting optics with a 1-3/4" diameter objective. The main tube is leather bound and the brass is generally blackened to minimize reflections. The objective lens itself is split into two semicircular segments mounted independently and driven in opposite directions by long screw micrometer gearing, with geared readout wheel graduated 0(0.5)60 twice and labeled "1 Degre" and with a note that each division represents one-half arcminute (of angular separation between the images). A simple graduated scale to the front indicates the coarse lens separation in degrees (0±2). The front is technically impressive, the blackened brass contrasting with dozens of bright lacquered brass mounting screws in a variety of sizes. Condition is good and functional, noting scuffing to the leather and a few scratches to the lens.

In use each half of the objective forms its own image, so one sees any object double. By adjusting the physical separation of the lenses, one can align the two images with the two ends of an object of known height or length, and thus know the range, the distance away. Thus one rather easily and accurately keeps station at sea, or determines the speed of gaining or losing on an enemy vessel, or time to landfall.

Edmond Lorieux was apparently trained by Gambey, and c. 1845 established what became a very important manufactory of navigation instruments. He was succeeded by Hurlimann, then by Ponthus and Therode, then Ponthus, and finally Lepetit (see Marcelin). We have catalogued one other micrometric telescope by Lorieux (pere), that one much larger (22" long extended), and labeled a bit differently "Micrometre Lugeol, a cadran de Lorieux," i.e., the Lugeol system, with dial plate readout (Tesseract Catalogue 53 Item 28). (9171) $2950.



A Hallmarked Miniature Click on any image for a larger view.

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A MINIATURE SOLID SILVER OCTANT, English, 1979, fully hallmarked for London sterling silver of 1979, and with maker's mark. The flat frame measures 5" (13 cm) tall. This diminutive, more-or-less functional "replica" of an 18th century octant has a peepsight, horizon mirror, hinged filter, and index mirror on moving arm. The scale is divided in zenith distance every degree from 90° to 0°, with transversal interpolation, and with readout against the index arm's line of faith which is sub-divided every 10 arcminutes. The arms display floral decor, and the center presents an unusual fish or sea monster. Quality is modest; condition is very fine. Although hardly an antique, at just over 30 years of age, this is nevertheless an amusing, solid silver honestly hallmarked piece which can demonstrate the principles of celestial altitude measurement and transversal interpolation. (9275) $595.


For Sextant Use when the Horizon is Obscured Click on any image for a larger view.

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ARTIFICIAL HORIZON OUTFIT, English, c. 1900, contained in the original 8" x 4-1/2" x 1-3/4" (20 x 11 x 4 cm) fitted mahogany case, signed "Stanley, Great Turnstile, Holborn, London." The finely made brass cell, finished in beautifully contrasting chemically darkened and clear lacquered finishes, contains a flat dark glass and is mounted with three leveling screws. Also provided is a tubular glass spirit level, one side ground flat. Condition is excellent. With the spirit level set on the black glass plate, one levels the instrument very precisely by adjusting the three screws while repeatedly turning the level by 90°. Then with a sextant, for example, one can measure the angular altitude of a celestial body by measuring the angle between the body and its reflection in the mirror, and dividing the result by two. No knowledge or view of the horizon is required, an exceptional advantage when the horizon is obscured by low fog or haze, or mountains, etc. (9222) $795.


From English Maker to French Royalist Click on any image for a larger view.

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SIGNIFICANT PRESENTATION TELESCOPE IN SHEFFIELD SILVER, English, early 19th century, stamped on the first two drawtubes "Berge, London late Ramsden," and engraved around the objective mount "de M. Berge à M¹r. Emery dit hermély, 1822." The telescope opens from 7" to 20-3/4" (18 to 53 cm) with a mahogany maintube and three drawtubes and mounts of heavy silver over copper. It is fitted with a greenish triplet achromatic objective and erecting optical system giving fine images. Condition is very fine noting the eye cap replaced.

This telescope records an interesting history, having been made by Ramsden¹s successor, Matthew Berge, and presented to the famous Jean Marie Emery dit Herméley (1769 - 1850). The sailor and later lieutenant Emery (who went by the name Herméley) served under Georges Cadoudal in the underground chouanne army, as a Royalist, against the French Revolution. (9255) $2800.


From an Important New England City Click on any image for a larger view.

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AMERICAN COURSE RECKONER, Maine, c.1880, stamped on the arm "J.W. Strange, Manufacturer, Bangor, Maine, Pat'd June 13, 1876," all brass, 15-7/8" (40 cm) overall, with a rotating 4" diameter compass rose divided into 128ths of a circle. Made for direct charting of course headings, this unusual American invention has its original lacquer finish, and is in excellent condition but for one small stain and tiny dent. J.W. Strange is listed in the directories as a die cutter and machinist. The present combination of protractor and T-square was patented by J.D. and S. Leach of Penobscot, Maine; we note that Strange was careful to identify himself as "Manufacturer." (8238) $695. (SOLD)



Precision Pocket Sextant from Aberdeen Scotland Click on any image for a larger view.

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A SCOTTISH BOX SEXTANT WITH TANGENT SCREW FINE ADJUSTMENT, c. 1830, signed "Ramage, Aberdeen." The 3" (7.6 cm) diameter brass drum-shaped sextant has a removable cover that screws onto the back as handle. The finely crafted miniature sextant itself has inlaid silver scale and one-arcminute silver vernier, scale magnifier, swinging index arm and mirror with the most unusual feature of clamp and long tangent screw fine adjustment, insertable red and green filters, optional peephole or single drawtube telescope with screw-on solar filter, and mirror adjusting tool. Condition is very fine with original stitched leather outer case, noting case and cover with some wear. The sextant itself is beautiful with its original bright lacquer finish.

This is a fine example of the "snuff box" sextant, useful for exploration on land, navigation at sea especially on small craft or lifeboats, etc. But it is very special for having a precision long-screw fine adjustment to the index arm position. We know of another such instrument, in the National Maritime Museum, that with the same sort of raised quadrantal clamp plate, pierced with three holes, but signed "Adie, Edinburgh." (9191) $1450.


Complex Form of "Davis Quadrant" Click on any image for a larger view.

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EXCEPTIONAL BACKSTAFF WITH SOLAR DECLINATION SCALE, English, 1739, signed on the boxwood crossbar "London, Made by E. Blow in Half Moon Court by ye Hermitage, Wapping, 1739," and on the main arm "No. 87." There is also a blank inset ivory owner's plaque. Finely constructed with rosewood (?) structure and boxwood arcs, this early navigational instrument measures 25-1/4" (64 cm) overall. The two concentric arcs, centered on the far end, are graduated in degrees and form a total angle of 90 degrees (hence traditionally named The Quadrant, or Davis's Quadrant). The lesser arc (cleverly made of small radius to lessen the size of the instrument) is graduated every degree from 0 to 65, and has secondary scribe marks on the edge, slightly offset, to account geometrically for the 16 arcminute semidiameter of the sun. The greater arc is divided every 1/6 of a degree (i.e., every ten arcminutes), and with transversals dividing to one arcminute. The scale runs from 0 to 25, and back from 65 to 90, for readout in either altitude or zenith distance.


Additionally, the greater arc has a set of solar scales on the reverse. Beginning on 10 March (the vernal equinox, and thus good evidence that this instrument predates the 1752 adoption of the Gregorian calendar in England) there are linear date scales (divided for every day of the year) separately for the sun North and South of the celestial equator, and a corresponding nonlinear scale of solar declination (0 to 23-1/2). Thus a sight vane could be positioned to the date, with readout of the solar declination, and simple determination of one's latitude from a measurement of the sun's altitude at noon. In our experience these scales are found on a very small number of surviving instruments. There are decorative stampings of five-lobed roses, fleur-de-lys, and geometric patterns. Condition is fine noting light wear; there are no sight vanes.

The backstaff was a vast improvement on the cross-staff, which required the navigator to sight in two directions simultaneously (not to mention looking directly at the sun). Most observations were in fact to determine the solar meridian altitude, and thus the ship's latitude. Observing with the backstaff, the sum of the readouts on the greater and lesser arcs was the solar altitude. This required correction for the solar declination on the date, provided directly on the scales here, without resort to tables.

The maker was Edmund Blow, son of a "hemp dresser," free in the Joiners guild in 1704, instrument maker in Wapping from then until 1739. He is known to have made Napier's bones as well as backstaves, and may have worked exclusively in wood. Another backstaff by him is recorded, a fine example dated 1736 and now in the Whipple Museum.

A handsome example, signed, dated, and serial numbered. (8187) $13,500.


Innovative Twin-Mirror Full-Circle Outfit Click on any image for a larger view.

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THE HYDROGRAPHIC CIRCLE OF ROLLET DE L'ISLE, French, late 19th century, finely signed "Lorieux, A. Hurlimann, Succ'r a Paris." The 10-1/2" (27 cm) diameter brass circle is fitted with four mirrors, two of them mounted on the rotating index arm and set back-to-back at a fixed angle, a large-light-gathering-power telescope, and a hinged turned wood handle. An inset circular scale is divided every 0.5 from -10 to +200 half-degrees. The index arm has clamp, fine motion tangent screw, vernier to one-fiftieth of a degree, and magnifier. The instrument is equipped with its full complement of accessories, all original: two solar filters, two right angle sights, seven interchangeable filters, two adjusting tools, three spare mirrors, fitted mahogany case 13" (33 cm) square, and key. Only the screwdriver and loupe are lacking. Condition is absolutely superb throughout. The circle functions basically as a sextant, except there are two "horizon" mirrors, and two "index" mirrors, disposed so that one pair is useful at smaller angles, the other pair at larger ones. Readings are possible from 0 degrees straight ahead all the way to 180 degrees directly behind the observer -- as one mirror view becomes foreshortened, the other takes over automatically.

This is the remarkable invention of M. Rollet de l'Isle, French hydrographic engineer to the Marine (and world-famous proponent of the Esperanto language). It was still advertised in 1911 (by Ponthus & Therrode, successors to Hurlimann, who in turn was successor to the well-known firm of Lorieux established in 1845), as the model adopted by the French hydrographic marine services. A very rare example of this innovative design, in splendid condition. (8194) $7200.




A True "Sliding Gunter" Rule Click on any image for a larger view.

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RARE NAVIGATIONAL SLIDING GUNTER, English, c.1800. This uncommon slide rule is made of boxwood, brassbound, with a 25" (63 cm) long central slider. Rule and slider are divided on both sides with logarithmic and trigonometric scales, including Chords, Rhumbs, Numbers, Sine Rhumbs, Sines, Versed Sines, Tangents, Tangent Rhumbs, Longitudes, Meridional Parts, and Equal Parts, the latter two designed specifically for sailing by Mercator's chart projections. Condition is fine throughout. A description of the "sliding Gunter" is found in Norie's A New and Complete Epitome of Practical Navigation (8th ed., 1825); it bears considerable similarity to the sliding navigational rule invented by John Robertson (1712-1776) and published by William Mountaine in 1778. In 1807 Mackay wrote, in The Complete Navigator, "But the most convenient form of this instrument [the "common Gunter's scale"] both for accuracy and dispatch is that known by the name of the SLIDING GUNTER, in which the use of a compass is superseded." We find one quite similar rule in the Science Museum collection (Inventory #1921-676). A rare and significant navigational instrument. (7263) $1950.



Important Connecticut Invention by Captain Townshend Click on any image for a larger view.

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TOWNSHEND'S DOUBLE REFLECTING CIRCLE -- AN EXCEPTIONAL AMERICAN NAVIGATIONAL INSTRUMENT, c.1890, signed "Townshend, Patd. Jan 31, 1888," and "Stackpole & Brother, New York, 2204." The instrument is made of brass, with 8" (20 cm) diameter six-spoked main circle inset with silver scale divided every ten seconds of arc and labeled with double degrees 0 - 180 (on two sides), and 0 - 720 full circle. Two mirrors are mounted independently at the center of rotation, each with vernier (divided every ten arcseconds thus reading to 20 seconds in double degrees) arm and magnifier. Each mirror arm can be adjusted manually by long control rod, or driven in fine motion by clamp and tangent screw. One views through the adjustable telescope to the fixed mirror (with one clear and two silvered areas itself mounted tied to the telescope on long arm with clamp, tangent screw, vernier, and magnifier), then to the adjustable mirrors and to the targets. Thus one can sight three objects and measure two angular separations simultaneously (as two bright stars from the moon, for the lunar longitude method, or three coastal landmarks, for triangulation in coastal navigation). It is equipped with mahogany handle, two interchangeable achromatic telescopes, one sighting tube, screw-on solar filter, three insertable rectangular filters, and the original fitted mahogany case. Condition is very fine noting a little spotting to the original lacquer finish. Captain Townshend (1833 - 1904) was a resident of New Haven, Ct, and recommended his device for sighting sun, moon, and fixed stars, etc. Very few examples of his double reflecting circle have survived -- we can locate only those at Mystic Seaport and in the New Haven Colony Historical Society, one in a private collection, and the one offered in Tesseract Catalogue 50, Item 26. An important find. (8152) $14,500.












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