Mint D.W. Bruntons Pocket Transit/Compass Wm. Ainsworth & Sons #84079

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Mint D.W. Bruntons Pocket Transit/Compass Wm. Ainsworth & Sons #84079 :
$449.00

Mint D.W. Bruntons Pocket Transit/Compass Wm. Ainsworth & Sons #84079.
Beautiful Brunton Leather Case and Operating Instructions included. Immaculate Brunton Case is Heavy Duty Thick Leather with Belt Loop & Brass Snap & Rivets.This absolutely Mint Vintage Precision Instrument is the famous Brunton Pocket Transit designed by Colorado mining engineer D. W. Brunton and #84079 was used by my uncle to help map coastal Alaska with the U.S. Geological Survey. After that it spent the next 50 odd years in his safe so unlike most of these fine field instruments it is perfectly preserved.This is the desirable weatherproof model with the rubber gasketed bezels.In 1894 Brunton received a patent for his new compass and within a few years it became widely used throughout the world and the Brunton Compass remains many geologist\'s most trusted tool, combining the principles of the surveyor\'s compass, prismatic compass, clinometer, hand level, and plumb. It unfolds to produce two sights with peepholes. You can either sight through a clear window in the lid or lay the lid fully open and use the second hinged peep sight. The inside cover has a mirror with a vertical line inscribed. The Brunton Pocket Transit features a single NdFeB magnet that resists demagnetization better than other types of magnets for increased reliability. The compass needle has a sapphire jeweled bearing and is induction damped needle for quick and high accurate readings. The perimeter of the face has a compass rose and the interior of the compass rose has two spirit levels and a movable scale for use as a pocket transit. There is a slotted screw on the outside of the case that turns a gear that rotates the entire compass rose to adjust your local magnetic declination angle (the difference between true north and magnetic north). Closing the compass lid moves a needle lift mechanism that protects the jewel bearing when transporting the compass.Turning the compass on its side and adjusting the spirit level allows for an altitude angle measurement (while viewing the spirit level using the mirror hinged at 45-degrees). The Brunton Pocket Transit is accurate to 1/2 degree in azimuth, and has a 10 arcminute resolution for vertical angles. The compass measures 2 3/4 inches (7 cm) by 3 1/16 inches (7.8 cm), is 1.25 inch (3.2 cm) thick, and weighs 6.5 ounces (184 grams). DESCRIPTION by The National Museum of American History of their Brunton Pocket Transit:
\"The Brunton Pocket Transit was said to be \"the most convenient, compact and accurate pocket instrument made for preliminary surveying on the surface or underground.\" It has a folding sight at north. The lid of the instrument, hinged at south and provided with sight line and small hole, serves as the second sight. Since the lid is mirrored, the user can read the needle while sighting a distant object. The needle ring is graduated to degrees. The western half of the face is graduated in degrees, in quadrants from west, and provided with a clinometer with vernier that reads to 5 minutes. The sides of the case and lid are flat, and so the instrument can be set up vertically when used for vertical angles.\"David W. Brunton (died 1927), a Canadian–born surveyor working in Colorado, invented this instrument after growing tired of carrying heavy equipment through the Rocky Mountains. He obtained his first patent (#526,021) in 1894, and subsequent patents in 1912 (#1,042,079), 1913 (#1,062,582), and 1914 (#1,092,822). The Wm. Ainsworth Co. of Denver began marketing these instruments in 1896, and by 1899 had sold more than 200 units. The firm became Wm. Ainsworth & Sons in 1905...\"\"Ref: Wm. Ainsworth & Sons, Catalog BX of Precision Engineering and Surveying Instruments (Colorado, 1908), p. 62.Peter von Gitter, \"The Brunton Pocket Transit, A One Hundred Year Old North American Invention,\" Earth Sciences History 14 (1995): 98–102\"This item comes from the quality collection of a Career Winchester Factory Research Lab Metallurgist, Firearm Expert & Collector & Distinguished Expert Camp Perry National Match Team Marksman. Please see my other items being offered from this collection and continue watching my sales over the next several weeks for more vintage outdoors items, vintage gun parts, gear & scopes, reloading tools, gun books, vintage gun catalogs, vintage gun magazines, manuals, vintage cartridge boxes etc, etc..
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