Photos of Navigation Instruments and Model Instruments

English vernier sextant, c. 1900

Description: Brass construction with black oxidized frame, index arm, mirror and filter mountings (all now with a light green patina), bright lacquered telescopes and fittings (the lacquer finish is pitted to varying degrees, except in the case of the long telescope in which the finish is entirely missing), and a polished rosewood handle. The hand engraved, 7 3/8” radius, inlet silver scale is graduated from -5°—145° by 10’ of arc (figures engraved at 10° graduations and diamonds at 5°).

The scale may be read to 10” with the vernier scale (see closeup of vernier scale at left), clamp & screw fine movement, and swing out magnifier.

The instrument is engraved english at the far left of the scale arc, and G.E. Butler, San Francisco. (in script-see image of engraving above) near the center of the arc (Geo. E. Butler Co. was a nautical instrument dealer in business in S.F. until at least 1984).

The instrument has three horizon glass and four index mirror filters built onto the frame. The long telescope (7 1/4” closed) and short wide field telescopes have complete optics.

There is also a short telescope barrel (no optics), a shade tube (eyecup missing?), brass ball tipped adjusting pin, and a folding hand magnifier in a tortoise shell (?) case (Lens badly chipped). There is an empty place in the case for a telescope eyeshade.

The original mahogany case, 10 3/4 x 9 7/8 x 5” is in good condition, with splits at screws/nails at three corners each of the top and bottom panels-(see image of case at left).

The case itself is of hand dovetailed frame construction (see closeup image of the dovetails, with layout lines clearly visible to the right), with the top held on with brass wood screws and the bottom held on with steel nails. Inside the green felt lining is water damaged, the hinge has a red oxide patina, and the lid has been owner modified (gouged out) to allow the wide field telescope to remain in place on the sextant during storage.

There is a brass name plate, engraved Stream with many flourishes, set into the top of the lid (see engraved plate above). The hook catches for the lid are chemically darkened brass, while the handle is age polished. The key is a replacement.

There were two trade stickers in the lid of the case, the first: max kuner co. / nautical instruments / {k-2786|4031}*/ chronometer & watchmakers /804 first avenue / Seattle

and the second, (now removed) Northwest / Instrument Co. /Nautical & Surveying instrument makers / 63 Madison St. { N-9588} Seattle,Wash.

*Figures enclosed in {} indicate handwritten text.

The sextant was owned by Thomas W. Stream (lost at sea in January of 1914), Master of the Edward R. West, an 835 ton Schooner, out of San Francisco CA. (click for image link to U. Wash. Library image)

Sextant Micrometer Detail

Detail, US Navy micrometer sextant, inscribed "David White Co. Milwaukee, Wis." and "U.S. NAVY, BU. NAV. MARK II (N)* 17424 - 1943" (see closeup of logo below) . A similar ( but with adjustable polarizing filters) instrument is in the NMAH collection and is described and illustrated at: http://amhistory.si.edu/navigation/object.cfm?recordnumber=1273238

* The N is inscribed in a circle.

These instruments have a cast aluminum alloy frame with the arc graduated on the limb from -5° to 145° (see image of sextant, left). The micrometer reads to 0.1 minute = 6" of arc. The bronze gear is attached to the limb beneath the arc with screws. The index arm and telescope are of aluminum with brass furniture and nickel-silver screws etc. The handle is made of mahogany.

image of case

The 11.25" square by 5.5" deep box is constructed of 5/16" mahogany plywood with dovetailed corners. The 1/4" mahogany plywood top and bottom are attached with screws. There is a metal tag on the front of the case.

image of sextant in case

detail image of dovetail joints

closeup of logo

image of tag

Octant, c. 1800

This octant has a radius of 13 3/4 inchs (index arm bearing center to vernier edge), while the greatest dimension of the ebony frame is 15 1/8 inchs. The ivory scale is graduated to 20' and can be read to 1' using the vernier. The scale is marked (between 45°&50°) with the Spencer, Browning & Rust "SBR" logo, showing it was graduated between 1785 and 1840 when this firm was in business. (What appears to be a nearly identical instrument but with original parts and micrometer adjustment can be seen at the NMAH [Smithsonian] collection.)

I obtained this octant in the Summer of 2012, for use in demonstrations and courses on instrumentation/navigation that I teach, and restored it, including fabricating a variety of missing parts. The photos above are of the restored octant. All bright brass parts/furniture and the "ivory" pencil are replacements I fabricated. Restored parts were left bright to show as replacements. A six inch rule is included in each photo. Additional photos, including some detail shots of the restored instrument are available shown below.

Restored Octant, obverse with 6" rule

Restored Octant, reverse with 6" rule

Octant case, closed, showing hook latch.

Octant in open case.

Close-up of replacement backsight.

Close-up of restored backsight adjustment hardware.

Close-up of restored furniture (all bright brass pieces were fabricated by R. Paselk).

Close up of replacement Pencil and Screwdriver made by R. Paselk. The "ivory" pencil cap was turned from clean bone (from a commercially availble "dog-bone" I stole from my dog) with a commercial 1/8" dia. pencil. The screwdriver cap was turned from yellow brass with a force-fit screwdriver made from 1/8" drill-rod. Both caps were threaded with a 6 x 1 mm metric die (by trying various bolts in my collection this size was found to fit loosely, with proper thread alignment). After cutting the threads were tapered by hand with a file to match the tapered hole in the octant.

After taking the photos above I recieved pictures of some original octant screwdrivers and found that the handles are flattened. As result I modified my screwderiver as shown in the picture.

Museum examples of original octant pencils and screwdrivers

Photos of original octant screwdrivers in the collection of the National Maritime Museum, Greenwich (NMM), are available below. All photos were kindly provided by Richard Dunn, Senior Curator and Head of Science and Technology at the NMM, They are listed by the catalog numbers for the associated octants:

NAV1259: Screwdriver, full view

NAV1259: Screwdriver handle, rotated 90°

NAV1261: Screwdriver with rule

NAV1261: Screwdriver rotated 90°

NAV1262

Above, Screwdriver with rule

Right, Screwdriver in octant

A photograph of an original octant pencil, in the collection of the National Maritime Museum, Greenwich, was generously provided by Juergen Hoefeld.

I also made replacements for all mirrors since the original silvering had badly degrade on all of them (the original mirrors are stored with the instrument). All replacement mirrors were cut from a thin glass commercial mirror-tile. The half silvered mirrors were prepared by scraping the backing (including the copper and most of the silver) off the desired clear window area with a razor blade and then dipping in 1 M nitric acid to remove the remaining silver. The resulting mirrors are quite functional for my purposes of demonstration.

Details of other fabrication processes will be posted later, or interested parties can contact me.

Finally, I constructed a carrying case for the octant and its case from teak and teak paneling recovered from a refurbished law office in L.A. The case is lined with recovered polyethylene foam cut to fit the octant's case.

Reproduction Instruments

"Columbus" solid-disk mariner's astrolabe

Life-size reproduction of a c. 1500 instrument in copper sheet by R. Paselk.

Mariners astrolabe

Life-size reproduction of a late 16th century instrument fabricated from 1/4" bronze plate by R. Paselk.

Mariner's quadrant

Reproduction fabricated from 1/8" copper-nickel alloy by R. Paselk.

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