3. Nautical Instruments

3.85  CHART DIVIDERS.  A very clean pair of navigational chart dividers in nickel silver, dating from the early 1800’s.  These dividers are probably English-made and are in excellent original condition.  They measure 5 3/8 inches long overall and effectively span a distance of up to 9 inches.  The action is very tight and secure.  A bargain.  39

3.49 TRAVERSE BOARD.   Extremely rare, late 1700’s mariner’s navigational device known as a “traverse board.”  This scarce survivor from the age of sail is Dutch in origin.  Known there as a “pinnkompass,” it was the primary component in the method of navigation known as “dead reckoning,” used by virtually all maritime nations of the era.  In essence it was a primitive  computer!  The board is of one-piece wooden construction in two sections with a large “eye” at the top for hanging when not in use. The upper section serves as the direction component arranged in the form of a compass rose with 32 lines representing the 32 points of the compass, radiating from the center.  Each line is drilled with 7 holes indicating successive half hour intervals of the 4 hour deck watch beginning with zero (no hole) at the center.  Used in conjunction with a half hour watch glass (sand timer) the direction steered during the recorded period was noted using a pin or peg inserted into the innermost hole on the appropriate course line.  Successive readings were similarly recorded progressing outward with each turn of the glass.  The lower half of the instrument was the speed component, used in conjunction with a chip log, line and a log timer to determine the ship’s speed.  Horizontally it is marked in knots. “1 – 10” with quarter knot fractions on the right.  This measurement was taken every 2 hours (hence “2, 4, 6, 8” on the vertical axis) by throwing the chip log over the side, timing its passage with a 30 second glass and counting the number of knots payed out in the line during that interval.  Thus the ship’s speed in “knots” was recorded.  The sum of the resulting speed and direction “vectors” was computed by the navigator at the end of the watch to give the captain a rough idea of his ship’s travel and its resulting position.

This rare instrument is made of a regional hardwood, probably oak, laminated on the working side with vellum and painted in its original light green paint on the reverse.  This construction technique is very similar to that used in making wooden diptych sundials during the 1700’s.  After it was firmly adhered to the board the vellum was meticulously hand-painted and the appropriate holes drilled.  The unusual writing across the bottom “GMYLEN G” stands for Mijlen Gevaren or “average miles sailed (per hour),” where mijlen is the more modern spelling of the archaic Dutch word mylen (miles) as shown.  The hand-painted rose was originally identified with the cardinal and intercardinal points of the compass.  But due to decades, possibly centuries, of use only “ZW” and “Z” (southwest and south) remain due to wear.  Telling of it age, the sizes of the holes vary from 1 to 3 mm in diameter indicating they were hand-made  using an auger or punch, not a uniform drill.

Overall condition is excellent for a wooden object of such vintage that was in constant use.  As noted above, it is well worn on the edges.  To these ends it does exhibit some old repaint around the periphery.  Under close scrutiny a few minor paint flecks of a slightly different hue can be seen on the vellum.  The paint on the reverse is well worn and the wood itself is alligatored with some expected worming.  An excellent sign of age and originality is the fact that the paint is not inside the worm holes, indicating the paint is older than the holes!  This rare relic of early navigation measures 11 ¼ inches high, 6 ¾ inches wide and is 5/16 to ½ inch thick.   A world class navigational instrument well over 200 years old and worthy of the finest museum. Price Request

Although at first glance primitive, this traverse board has some ingenious features, one of which is the alternating light and dark markings on the compass rose for ease of reading on the dimly lit deck of a ship in a dark night at sea.  Some 100 years later the British inventor Samuel Berry Singer received a patent for using this same concept to design a “night compass.”

3.84  EARLY MARINER’s  QUADRANT with MUSEUM PROVENANCE.   Particularly well-preserved navigational instrument dating from the late 1700’s, ex. museum collection.  This large octant, otherwise known as a “Hadley quadrant,” has limbs of mahogany, ivory scales and brass furniture.  It is of the double reflecting type, introduced by John Hadley to the Royal Society in 1735, after which such instruments saw acceptance and production in very nearly this same form for the next 100 years!  This example has distinctive characteristics which date it to circa 1790.  They include the existence of a backsight, mahogany vs. ebony construction, interchangeable filters, ivory pencil and large flat index arm with simple stop and left reading 0-20 vernier scale.  (See our customer help feature “History of the Sextant”).  This instrument is of classic form with an engraved ivory scale reading from -2 to 99 degrees signed with the “SBR” monogram indicating it was made by the prestigious firm of Spencer, Browning & Rust using their recent version of Jesse Ramsden’s dividing engine invented in the early 1780’s.  The ivory index arm vernier scale is calibrated from 0 to 20 minutes, providing an accuracy of one arc minute.  The frame is of mahogany (vs. ebony) indicating it is of earlier manufacture.   It is complete with its very rarely-found pencil for noting readings and small inland trapezoidal ivory notepad inlaid on the reverse.   The reverse also bears all of the brass fittings for adjusting the mirror boxes and all three brass “feet.”  This handsome instrument measures 16 inches long by 13 inches wide on the long arc.  The original case is constructed of hand-dove-tailed pinewood in its very desirable early deep blue paint.  Interestingly a number of the mariner’s original observations are penciled in the lid, making it a great, first hand, real time, intimate window into shipboard history!  The museum accession numbers “T266” are finely painted in red on both the instrument and its box.  The box measures 17 ½ inches long by 15 ¼ inches wide and 3 ¾ inches thick.  Aside from their already acknowledged rarity, such instruments hardly ever come to the market with their original boxes, and virtually NEVER in such fine, pristine, original condition!  This quadrant is well over 200 years old!!  Price Request

The venerable firm of Spencer, Browning and Rust was a prolific manufacturer of navigational instruments since the partnership was established in 1780.  The name appeared in the London Directories between 1780 and 1784 as being at 327 High Street, Wapping, London.   In 1798 the firm moved to 66 High Street and remained there into the 1840’s when the firm name became Spencer, Browning & Co. 

3.83  AZIMUTH INSTRUMENT.  Original, highest quality ship’s navigational instrument made by the esteemed American makers, “NEGUS NEW YORK” as stamped on the bed plate and again on the maker’s tag on the box.  This precision instrument is all brass with a blackened finish.  It has an optical quality glass prism which rotates via two knurled brass knobs.  Designed to be set atop the ship’s main steering compass in a binnacle, it has a magnifier set in a tube below the prism to enhance the current compass reading while at the same time providing an image of the sun or celestial body.  Two pivoting sun shades are provided for looking at the former.  A removable “line-of-sight” pole is provided, as is a bubble level for assuring totally accurate level readings.  This instrument was designed to fit over the top of a standard size 8 inch compass.  It measures 9 ¼ inches long by 3 3/8 inches wide and 8 ¾ inches high with the removable vertical post.  Absolutely mint, untouched, original factory condition in its original dove-tailed wooden box with brass hardware measuring 10 1/4 by 7 ½ inches by 5 ½ inches thick.  269

Primarily used to determine LAN (Local Apparent Noon) the azimuth instrument is an effective tool for determining the ship’s latitude by measuring the sun’s altitude at the exact time of meridian passage.

The Negus firm first appeared in the New York City directories at 84 Wall Street in 1850.  Thomas Stewart was trained as a chronometer maker in England and began working with his brother, John David in 1848, first under the name of Thos. S. Negus & Co.   During the Civil War the firm moved to 100 Wall Street and the name changed to T.S. & J.D. Negus.  The business of chronometer and navigational instrument making continued to grow, causing them to move to 69 Pearl Street in 1875.   From the Civil War onward, Negus enjoyed the patronage of the U.S. Navy as the suppliers of chronometers and other navigational equipment.   By the early 1900’s T.S. & J.D. Negus had established themselves as the leading nautical instrument makers and chandler in the United States.  In 1962 the firm was purchased by Max Low & Co.  Low found success in providing the government with navigational instruments, clocks and deck watches during World War II.  Max Low’s son, Charles, continued the business in New York through the 1980’s when the firm was finally dissolved.

3.70  EARLY 1800’s SEXTANT.   Class “A” mariner’s navigational sextant from the first half of the 1800’s.  The large arc is hand-engraved “Steele & Son, Liverpool” in fancy cursive script. This fine instrument features a classic braced brass frame with elliptical center.  The brass arc is inlaid with silver, precisely-divided from -5 degrees to 115 degrees calibrated in 10 arc minutes.  The silver vernier scale, marked from 0 to 10 allows a reading down to a very accurate 10 arc seconds.  To facilitate this reading a pivoting adjustable index arm magnifier is provided.  The reading is set by a knurled thumb screw and a tangential thumbscrew fine adjustment knob.  This exceptional instrument is complete with its full set of 3 horizon filters and 4 index filters, all in good condition.  Importantly, both the index and horizon mirrors are in tact.  On its reverse are the original brass “feet” and its sculpted ebony handle of early form.  It measures 10 ¼ inches wide on the arc and the index arm is 9 ½ inches long.  It is comes with its original hand-dovetailed box of rich mahogany measuring 10 1/8 by 11 ¼ by 5 inches thick.  The box is complete with all 3 original optical telescopes, including eye piece sun filter and mirror box adjusting wrench.  The original brass skeleton key lock is in place and functional with its original key!  What is remarkable is that this instrument contains two original Steele labels in the lid charmingly illustrated with old navigational instruments and packed with copious information of the period.  2 brass pivoting hooks assure the hinged lid’s positive closure.  Overall condition is absolutely wonderful.  There is a slight age crack in the lid of the box which is the norm -- expected of pre-plywood boxes employing large panels of solid wood.  Otherwise it is essentially perfect and totally original!  A real bargain for such an historic and beautifully-constructed instrument over 160 years old!  Priced to sell! SOLD
 
John Steele & Son worked as mathematical instrument makers, opticians and stationers from 1828-1851. They were located at 9 Duke’s Place, Wapping, London from 1829 to 1838 and at 21 Duke’s Place Liverpool from 1839 to 1851. They were succeeded by John P. Steele & Co. and associated with the famous maker John Crichton (worked 1831-1865) to whom Robert Steele (the son) was apprenticed. (Gloria Clifton, “Directory of British Scientific Instrument Makers 1550-1851,” 1995, The National Maritime Museum, Greenwich. Page 265).

3.41  MARINER’s QUADRANT.   Very rare, museum-quality navigating instrument from the age of sail.  This 18th century quadrant, otherwise known as an “octant” is signed on the flat brass index arm in engraved script, “GILBERT & GILKERSON  ~ Tower Hill London.”  This early astronomical angle measuring device has limbs of mahogany with inset ivory scales and brass furniture.  The index arm is 16 inches long overall and terminates in an engraved vernier scale on ivory which sweeps over the large ivory scale divided from -1 degree to 99 degrees divided by 20 arc minutes.  The vernier, divided from 0 – 20 allows a reading down to one arc minute.  The single thumbscrew stop on the index arm (without the later form tangential fine adjustment) belies this instrument’s 18th century origins.  The fact that the large scale effectively describes an arc of 90 degrees is the reason such instruments were known as “quadrants.”  This example has a double peephole foresight and a single antiquated “back sight.  All three mirror boxes are present as is the full set of 3 interchangeable sun filters.  A blank ivory nameplate is inset into the cross brace and the rarely-found ivory pencil is still in place.  The brass index arm stop is present on the right limb.  On the reverse, this instrument retains all three brass “feet,” trapezoidal ivory note pad for recording readings with the pencil, and a complicated set of adjustments for the two horizon mirrors.  In short this rare surviving relic is totally complete and in an outstanding state of original preservation.  Complete in its old original keystone pinewood box.  Interestingly, several notations from actual readings are scribed on the interior in pencil and in chalk.  The instrument itself measures 13 inches wide on the arc.  The box measures 18 inches long by 15 inches wide and is 4 inches thick.  The box is surprisingly sound and in great condition.  SOLD 

The partnership of William Gilbert and James Gilkerson was begun in 1793 as mathematical instrument makers and opticians at 8 Postern Row, Tower Hill, London.  They were succeeded by Gilkerson & Co, in 1809.  The partnership was known to have made and sold sextants, rules, globes and ring dials.  William Gilbert was heir to a long line of mathematical and scientific instrument makers beginning with his grandfather, John Gilbert (I) in 1719 and his father, John Gilbert (II) in 1751.

(Gloria Clifton, “Dictionary of British Scientific Instrument makers 1550 -1851,” 1995, Zwemmer, Philip Wilson Publishers, London).

3.82  NAVIGATOR’s CHART RULES.   Authentic early 1900’s English ship’s navigational rolling rules used to lay out courses on navigational charts.  This heavy solid brass parallel ruler is marked “U.W.W. MAKERS BIRMINGHAM.”  It consists of two interconnected rollers with finely crossed striations used to grip the charting surface.  In so doing they provide a parallel motion which can be traced from a compass rose on the chart to the ship’s line, indicating the plotted course in degrees.  The body of the rule measures 18 inches long by 2 ½ inches wide with beveled straight edges on both sides.  Two knurled brass handles, one on either end, allow the navigator to readily move the ruler across the chart.   The rule is stamped with the owner’s name “J.J. RIACH.”   It comes in its original hinged wooden case of dove-tailed construction with brass hinges.  The case measures 19 by 3 ¼ by 2 inches.  Excellent condition throughout.  Makes a perfect presentation as a noteworthy nautical gift. SOLD

3.81  MARINER’s QUADRANT.  Very rare, highly desirable 18th century navigational device known as a quadrant, or alternatively “octant.”  This early example is patterned after John Hadley’s double reflecting quadrant first introduced in 1731.  It is an extraordinary instrument which has limbs of mahogany with brass furniture and a finely engraved boxwood scale inlaid into the large arc.  The scale is divided from 0 to 90 degrees, or one quarter of a circle, hence the designation “quad”rant.  The degrees are marked by 5’s.  Each degree is sub-divided into 20 arc minute segments, with diagonal lines cutting across 10 concentric circles.  With this arrangement the index arm and its ivory “line of faith” can provide a reading to an accuracy of 2 arc minutes, interpolated to 1 arc minute.  Below the diagonal scale is a second linear scale divided into single degrees and subdivided to 20 arc minutes.  These precise divisions are quite remarkable considering they were hand-done, before the advent of the mechanical dividing engine!  To attain such accuracy the instrument was necessarily large.  The index arm is slightly over 18 1/2 inches in length and the scale is 15 inches wide.  The quadrant is equipped with an index mirror and horizon mirror, a set of three pivoting filters, and a peep sight with pivoting shade.  It has a blank ivory nameplate in the cross brace.  On the reverse are three brass “feet” and the horizon mirror box adjusting assembly.  The index arm stop is a single brass thumb screw.  There is no fine adjustment feature on these early instruments.  Condition is remarkably excellent for a working device which saw sea service over 240 years ago!  A true museum piece! Price Request

The search for “The longitude” in early 18th century England was encouraged by the Board of Longitude which offered a massive prize of £30,000 for the solution.  It spurred much innovative interest in celestial navigation.  In May 1731 John Hadley, an English mathematician, presented a paper to his fellow members of the Royal Society in London describing the use of a double reflecting quadrant or "octant."  His quadrant was based on the principle of light reflection and angles of incidence that were described by Robert Hooke, Isaac Newton, and Edmund Halley in the previous century.  The principle is that when the angle of a celestial object and the horizon is seen through a double reflection, that angle is condensed in half between the two reflecting surfaces.  Thus Hadley's quadrant, reading to 90°, had an arc of only 45°, or one eighth of a circle, making it an "octant."  Basically the instrument consisted of a triangular wooden frame with a swinging index arm pivoted at the apex.  A mirror was fixed at that point which would move with the arm.  A second mirror, half of which was transparent so that the user could view the horizon, was fixed to one limb and a sight was attached to the opposite limb.  A precise scale, calibrated in degrees, was scribed on the arc of the bottom limb of the triangle, across which the index arm moved.  This continued to be the basic form of angle measuring navigational instruments for the next 250 years, and still remains, even with the advent of GPS!

Quite independently of Hadley, Thomas Godfrey, a Philadelphia glazier and acquaintance of Benjamin Franklin, devised an improved altitude measuring device based on the same principle over a year earlier.  The instrument had been tested in the sloop TRUEMAN on voyages to Jamaica and Newfoundland from 1730-1731.  The Royal Society recognized the equal contributions of both men and awarded them a prize of £200 each.  Godfrey also received a prize from the Board of Longitude (of chronometer fame) for his work.  However it was Hadley who ultimately received the most credit for the invention.

The improvements in navigation of the Hadley quadrant or "octant” as it came to be known, over previous instruments was immense.  Not only was it more accurate, it provided simplicity of operation, and the ability to "capture" the object being sighted for rapid, multiple sightings.  The merits of the quadrant were immediately noticed by the British Admiralty and its commercial production was begun.  Even so, the instrument did not find popular acceptance and general use amongst traditionally minded mariners until after 1750.

The earliest Hadley quadrants, like backstaves, were constructed of walnut or other indigenous woods, with the scales being engraved on boxwood (although examples on brass do exist).   With the discovery and growing importation of exotic woods such as ebony, rosewood and African mahogany beginning in the 1750's, the use of mahogany was quickly implemented, gradually giving way to the exclusive use of ebony, then ultimately brass by the mid-1800's.

From the article “Evolution of the Sextant” by Rod Cardoza
http://westsea.com/captains-log/evolutionofthesextant.html

3.80  PRESENTATION SEXTANT.  Truly exceptional first half of the 19th century British pocket sextant also known as a “box sextant.”  This fabulous example of the early scientific instrument maker’s art is all brass, housed in its original mahogany case.  This maker of this precision instrument is identified with the hand-engraved signature “T. Dunn, Edinburgh.”  It is inlaid with a scale of sterling silver calibrated in half degrees of arc from -5 to 140 marked by tens.  The fine silver vernier scale on the index arm provides an accuracy down to a single arc minute.  To facilitate the minute reading a pivoted magnifier is provided.  What is truly exceptional about this instrument, placing it far above most others of its type, is that it actually has a fine adjustment tangent screw, typically only seen in much larger sextants of the era.  Cleverly, it also has two pivoting sun filers within the body, actuated by levers on the periphery of the case.  A removable sight is also provided, which rests in the case when not in use.   The instrument is encased in a knurled brass cover which hermetically seals it when not in use, and acts as a handle when screwed onto the other side.  Adding more value and desirability it is beautifully engraved with the presentation “TO James Peddie FROM Geo.& Jas.s Gunn JUNE 1842.”  The quality of the engraving is the finest we have ever seen!  The instrument itself measures 3 inches in diameter and 1 ¾ inches thick.  The mahogany box of splined construction with original brass hook and eye closure and inlaid brass plaque measures 4 by 4 inches and 2 1/4 inches thick.  Remarkably pristine original condition after 174 years!  Certainly the finest box sextant we have ever had the pleasure of offering.  
Price Request 

Gloria Clifton, author of “Directory of British Scientific Instrument Makers 1550 – 1851,” 1995, The National Maritime Museum, lists Thomas Dunn on page 90 as a Mathematical, Philosophical instrument maker and Optician, working first in 1843 at 50 Hanover Street in Edinburgh, Scotland then at 106 George Street through 1867.  Thomas began his business with his brother, John Dunn II in 1841, who at the time was working in Glasgow.  It is interesting to note that the presentation date of 1842 predates Thomas’s move to Edinburgh, apparently still in the employ of his brother.

3.77  SEXTANT & OCTANT PARTS.  We now offer for sale a large variety of original old parts for 19th and early 20th century sextants, including filters, mirror boxes, mirrors, telescopes, peep tubes, sights, mounting feet, telescope holders, vernier magnifiers, individual glass sun filters, screw-on eyepiece sun filers, etc. etc.  The large diversity of this unmarked material is not identifiable by specific make and model.  However we can provide “look alikes” and “nearly the same” replacements for your instrument lacking same.  Prices are very reasonable for these authentic antique components compared to the cost of a newly fabricated replacement.  VARIOUS