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At the time I acquired this compass, it was my most exciting acquisition to date.
This is an older Ainsworth Brunton, which probably dates very close to the 1926 patent date listed. I am guessing it was made in the period between 1926 and 1928.
Specifications:
- Manufacturer: William Ainsworth and Sons.
- Date of Manufacture: Post 1926 based on patent date.
- Materials:
- Body: Aluminum
- Crystal: Glass
- Size: 3-1/16 X 2-3/4 X 1-1/4 closed
- Needle: Magnetic steel
- Damping: None
- Pivot: Jewelled
- Graduations: Degrees by 10, with tick marks at every degree and longer marks at every 5 degrees.
- Declination: Adjustable via screw-driven gear.
- Weight: 8.5 oz
- Stop: pin actuated by lid when closed.
- Description: This is a genuine Ainsworth Brunton Pocket Transit. The body of the instrument is unpainted aluminum. The face of the transit is also unpainted aluminum, with marks engraved on it. The inside of the lid contains a round mirror with an oval sighting window at the hinge side, and a center-line which is engraved perpendicular to the hinge, bisecting the oval sighting window. The side opposite the hinge has the small folding sight, which folds flat against the outside of the lid. The long sight is attached to the body of the compass, opposite the hinge. The long sight has a fold-up tip that allows the instrument to be laid out with an 8-1/4 inch sight baseline.
- Condition: Excellent. Needle swings free on jewelled bearing. Sights are present and intact, and move easily. The mirror is unbroken, clear, and free of any foxing or spots which is so common on older Bruntons. Retaining rings are in place and in good condition. There is some discoloration of the mirror retaining ring near the hinge. Level vials are intact, the fluid is present and clear and the bubbles have been retained. This is one of the more interesting features of this compass, and why I acquired it in the first place. After 1926, Bruntons were almost exclusively manufactured with the K & E 'round level'. The fact that this level appeared so soon after it's patent date in the Ainsworth line makes many collectors think that K & E Bruntons may have been manufactured by Ainsworth. However, this one has the 1926 patent date (which refers to the addition of the percent grade scale) but has the crossed long levels. As it turns out, a fellow collector located an advertisement by Ainsworth for their Brunton Pocket Transit, in which they offer the option of ordering it with the crossed level or with the new round level.
- Damage: Various nicks and scratches on outer case, as well as a wear haze overall. Black paint on brass parts is long gone. The varnish over the brass screw heads has worn onff in some cases, and where present has yellowed considerably, causing the brass screw heads to appear bright orange.
The declination adjustment screw has a missing tooth or similar damage inside which only becomes obvious when turning the screw. The declination ring moves, but there is a 'hitch' in one particular spot corresponding to a particular position in the rotation of the screw.
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