By Thomas Heath, with Ingenious Single-Transversal Readout Click on any image for a larger view.

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SPLENDID PROTRACTOR BY THOMAS HEATH WITH FIVE - ARCMINUTE TRANSVERSAL WINDOW, English, c.1725, signed "T:Heath Fecit." The 8" diameter (20 cm) semicircular brass protractor is hand-divided every degree, with beautiful bold numbering every 10° from 0° to 180° (and from 180° to 360°). The left side is pierced with a window and transversal running from 0° to 1°, itself divided every five arcminutes from 0 to 60. It is further pierced with a central rectangle, and decorated with bold elegant hand engraved "leaves" in the corners. Scales of polygon angles (from 4-sided to 12-sided) are laid out against the degree scales (from 90° down to 30° and up to 150°), and the base of the protractor is finely divided with a scale of four parts per inch, each part subdivided to tenths. Condition is generally fine throughout, noting minor signs of use.

Heath was an exceptional maker, but instruments by him appear infrequently on the market. This one is remarkable in its use of a transversal window, a feature we have seen rarely, once by Edmund Culpeper, and again by Heath (see Millburn's article SIS Bulletin 50, pp. 25-26). In use one measures an angle by placing the protractor's centerpoint on the angle's vertex, placing the crossbar more or less along the baseline (the first side of the angle) rotating the protractor slightly (less than 1°) until the second side exactly cuts an integral number of degrees (or half degrees), and reads the additional minutes where the transversal cuts the baseline. It is a practical, fast technique for reading (or marking) headings, etc. to five arcminutes or better. (7264) $3500.


Handmade in Burgundy Click on any image for a larger view.

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HAND CARVED FOLDING SQUARE / LEVEL / RULE, French, late 17th / early 18th c. This wooden "square" has hinged 6-3/8" (16 cm) legs, one pierced and notched for plumb bob and string. The legs are boldly cut with scales of Rhine inches ("Pouces du Rhin"), and of Kings inches ("Pouces de Roy") from 0 to 6 with subdivisions to twelfths, and with two further linear scales running 0 - 70 and 0 - 80 respectively. Condition is good noting slight wobble to the hinge. One leg is engraved "A autun," perhaps a clue to its maker, the city of Autun lying on the Saône-et-Loire in Burgundy. The first wooden example of this instrument we have seen. (7284) $495.


Invented by the Renowned Engineer and Surveyor of the Pennsylvania Coal Mines Click on any image for a larger view.

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KIMBER CLEAVER'S MARKING PROTRACTOR, American, boldly signed "Young & Sons, Philada., Pa." This very substantial instrument is made of brass, 6-1/2" x 6-5/8" (16.5 x 17 cm), with distinctive X-form superstructure carrying the 5" diameter divided circle, clamp and long tangent screw. The circle has a silver degree scale divided every half-degree and labeled with directional headings (e.g., SW 210°). The circle is mounted with four knobs for rotation and four spring-loaded marking pins. Rotation is very smooth and sure. There is an external one-arcminute vernier in silver. Condition is very fine, the brass darkening a bit. The instrument is quite handsome with its distinctive design and combination of finishes (clear lacquered and chemically darkened brass, blued steel springs, and silver scales).

We note a smaller example of this rare instrument in Tesseract Catalogue 70 Item 26. Kimber Cleaver (1814 - 1858) started out as a teacher, but quickly rose to become the great mining engineer of the anthracite coal regions of Pennsylvania. He developed various mining inventions, and his innovative protractor, but held no patents, preferring to benefit the common good. Cleaver is credited with the original idea of laying the Atlantic cable. His mother is recorded as a Quaker, but he allied himself with the Native American political party, eventually running for Governor on that ticket. The maker is the famous firm established by William J. Young (born Scotland 1800, died Philadelphia 1870). In 1813 he was apprenticed to Thomas Whitney, and went on to become America's foremost surveying instrument maker of the mid-19th century. The rugged precision construction of this device is quite like that on his examples of Burt's solar compass, and in fact on his production of Burt's solar sextant (see Tesseract Catalogue 43 Item 28). (9261) $2950.


Variable Spiral-Forming Drafting Instrument Click on any image for a larger view.

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THE HELICOGRAPH OF PENROSE AND BENNETT, English, c. 1850, signed "W. Elliott & Sons, 56 Strand, London," and "Registıd. Dec. 11, 1850, 2582" and "No. 2." Constructed of lacquered brass, with shafts of brass and steel, this precision spiral-forming drafting instrument measures 14" (35 cm) long overall. The main shaft has fixed at one end an elbow supporting a pin point which establishes the center of rotation of the whole instrument. Near the other end one attaches a carriage with two swiveling ivory wheels. The main assembly, which is free to slide along the shaft, is guided across the paper by a milled wheel set at an angle, which angle can be adjusted precisely against a strongly nonlinear scale, to determine the obliquity of the spiral and consequent rate of motion of the assembly along the shaft. This assembly carries the weighted pen (or pencil) holder, in a carrier whose position is adjustable along a short shaft. The assembly can be moved manually by a swiveling "handle." Condition is very fine throughout, complete with the original mahogany case.

The makers, the partnership of William Elliott (II) with his sons Frederick and Charles, were in business under this name for only three years (1850 - 1853).

The inventors, who registered their design in 1850, were Francis Cranmer Penrose (Architect) and George Forrester Bennett, of Trafalgar Square, London. The instrument is described in W.F. Stanleyıs Mathematical Drawing and Measuring Instruments (pp. 85 - 88 in our 1888 sixth edition), where it is regarded as a considerable improvement over the complex pulley systems of the past. Hambly discusses the present form, and illustrates the pulley form volute compasses made for George III, the pulley system of George Adams, and the 1857 "volutor" of H. Johnson. In all three one used interchangeable helical cones to achieve different spiral forms. Penrose and Bennettıs invention made possible an adjustable continuum of spiral shapes. Apparently very few early mechanical helicographs survive today. In particular we have found only one other example of the present form, that a gift by Stanley himself to the Science Museum, in 1876. (7287) $7500.


Victorian Full-Circle Protractor, c. 1862 Click on any image for a larger view.

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FINE VICTORIAN BRASS PROTRACTOR, English, c. 1862, signed "J. Gargory, 41 Bull St., Birm'm." This 6-1/4" (16 cm) diameter full-circle protractor is divided every degree from 0° to 360°, and back again, boldly labeled with easy to read numerals. Both crossbar and circumferential edge are beveled down to the surface of map or chart. Condition is fine, retaining much of its original lacquer finish.

James Gargory is listed as optician, jeweler, goldsmith, and mathematical, mining, surveying, and optical instrument maker. Clifton gives working dates of 1835 - 1862, always on Bull Street in Birmingham, but at the present address only in 1862. (9305) $325.


Patented American Ellipsograph Click on any image for a larger view.

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RARE AMERICAN ELLIPSOGRAPH -- F. BOWLYıS INSTRUMENT FOR DESCRIBING ELLIPSES, c. 1870, signed "F. Bowlyıs patent Janıy. 14, 1868." This most unusual instrument is constructed with framework of beautifully grained tropical hardwood, and with linkages and fittings of brass and boxwood. When closed up it measures 16-1/4" (41 cm) long and only 5/8" x 1-7/8" (1.6 x 4.8 cm) in overall cross section. The frame (whose form reminds one of a violin bow) has fixed point and index pointer for orienting and stabilizing on drawing paper, and the linkage terminates in a holder for pencil lead or ink pen (not present). A boxwood rule is graduated in half inches from 1 to 21, each divided in eighths, and has two sliding swivel clamps (for adjusting size and ellipticity) attached to an extending hardwood arm and to a sliding brass linkage respectively. The instrument is totally functional and in excellent condition throughout.

This unusual ellipsograph is the invention of Franklin Bowly of Winchester, Virginia. He claimed "The advantages of this instrument are, great simplicity of arrangement, expedition and convenience in its application, and accuracy with which it describes an ellipse of any desired proportions within wide limits of size, ..," and in 1868 he was granted U.S. patent 73,290. Bowly recommended the instrument for draftsmen in general, using pen or pencil point, but also to cut glass for pictures frames, etc., using a diamond point! Period literature acknowledged the invention, e.g., in Knight's American Mechanical Dictionary (1876). A beautiful example of this clever design, and the only one we have seen. (9273) $5950.


Swiveling Set of Large Boxwood Architect's Rules Click on any image for a larger view.

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REMARKABLE BOXWOOD DRAFTING RULES, English, c. 18th century, the four double-sided rules cut as single panes of boxwood measuring an extraordinary 3-5/8" x 11-3/8" (9 x 29 cm), and mounted as a swiveling set with brass hinge. Each face (except the backside of the bottom one), is divided with two sets of linear reduction scales with transversal interpolation to the one-hundredth part of one unit. Each scale is identified with a "5" and with a two-letter code (AD through AI, BK, BA through BG). Two scales have old hand-written ink labels "63 (68) to an inch." Condition is very fine throughout except for a number of stains just on the outer surfaces of the set.

This is the first such set of early drafting rules we have seen. They would be used with dividers to lay out, or read out, distances on scale drawings, with a choice of 14 scales. A century later one would find cased sets of individual rules, and made not of boxwood but of ivory or ivorine. (9253) $1650.


Scales for Official French Mapping, c. 1800 Click on any image for a larger view.

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IMPORTANT HIGH-PRECISION CHART RULE, French, c. 1800, signed "Ferat a Paris; Depot G'al. de la Guerre 81." This heavy gilt brass rule, 8-3/4" x 2-3/4" (22 x 7 cm), is exquisitely engraved on both sides with reduction scales of equal parts, the scales numbered 4, 5, 6, and 7. Each scale is linearly divided, with transversal scale at the end subdividing the main divisions down to 1/100 or 1/50 part. Designed for the metric system, they are labeled with the scale reductions and usages, e.g., "Echelle de 2 Millimetres pour 100 Metres (Pour les dites Cartes reduites et a graver)." Besides scales for the engraving of charts, there are ones for use on maps of the "Reconnaissances Militaires," and for the "Canevas de la Topographie" (the baseline grid topographic maps). Divided with high precision, one still sees many of the layout marks, and engraving guidelines. Condition is fine noting some scratches and minor discolorations. It is complete with its original protective card case.

This is the first "official" French rule we have had designed for the construction, engraving and readout of military charts. It was part of the War Department's "Depot General" which was charged with furnishing the necessary charts and plans to the armies, as well as training Geographical Engineers. It is further significant in being signed by the maker. Ferat is recorded from 1799 to 1806, relocating frequently, through four different Paris addresses over seven years (see Marcelin). The young Gambey worked for him. The fineness of Ferat's engraving is truly exceptional. (9221) $2800.


Good French Ironwork Click on any image for a larger view.

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FINE IRON OUTSIDE CALIPERS, French, 18th century, measuring 21-1/2² (55 cm) tall, they feature long three-leaf hinge plates with finely shaped recurved decoration leading to the inward-facing tapered four-sided points. The hinge plates form a full right angle builderıs square, when open to a scribe mark on the hinge. The hinge itself has beveled rectangle decoration leading to double-S supporters. In fine condition, a wonderful example of early outside calipers, for builderıs and / or gunnerıs use. (7276) $2950.


Local Measure from Alpine France Click on any image for a larger view.

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CHARMING PROVINCIAL ITALIAN RULE, 18th century, the 6" x 1-3/4" (15 x 4 cm) brass rule divided on both sides with scales of equal parts from 0 to 100 by 10's, with additional segments subdivided to units, and with transversal interpolation scales divided to eighths of units. One side is marked "Mesure de Savoye" each unit 1.15mm, the other "(Me)sure de Piedmont," 1.29mm. These are local measures from the Alpine region of Northwest Italy and Southeast France. With appealing "provincial" craftsmanship, it is in fine condition noting one end possibly clipped off. An uncommon local surveying / mapping / drafting rule. (9281) $495.

Defensive Dividers! Click on any image for a larger view.

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WROUGHT IRON DIVIDERS / DAGGER, European 17th /18th century. Measuring 13-1/2" (34 cm) overall, this rather primitive pair of dividers is well constructed, with a five-leaf hinge with pommel knob, twin tapering arms, and double hilt. It has a good "heft" for use as a dagger. Condition is good, apparently all original, noting some pitting to the surface. The application of the hilt to dividers, making them into a significant close range weapon, is well documented. For example, one finds a rather formidable 16th century dagger / divider compendium in the Museo Galileo in Florence, described by Bonelli and Settle. (7259) $2650.


"Old" and "New" Measure Click on any image for a larger view.

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UNUSUAL CALIPERS / FOLDING RULE, French, 19th century, 7" (18 cm) overall (closed), of brass with iron fittings and end stops. The folding rule is divided from 0 to 12 French inches, by twelfths, and from 0 to 10 centimeters, by millimeters. The hinge center has a charming pierced iron six-pointed star, and the rule closes on shaped stellate designs. A sliding clampable cursor fits over the rule, forming outside calipers with readout in old and new (i.e., metric) measures. The cursor is pierced with a six-pointed star on one side, and with a "G" (for the maker), on the other. Condition is good noting some corrosion to the iron. We have seen only one other example of this folding combination, that clearly by the same maker, and in fact signed "Gillot." (8307) $1450.















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