This is a high-quality dipping circle with a carrying case and accessories (not shown) signed "John Dover, Charlton, Kent". The apparatus stands 10.5" overall on three leveling feet. The 3.5" long dip needle mounts inside a glazed mahogany box fastened to the rotatable main plate. There is an accurate spirit level. The horizontal degree circle has a one-arc-minute vernier, clamp and tangent screw, and twin angular stops.

An external mechanism lowers the needle onto agate ways. Two turned brass pillars support the vertical circle with its inlaid silver degree scale. Twin one-arc-minute verniers and twin scale magnifiers rotate with the twin telescopes (for viewing the needle) on an assembly with clamp and tangent screw, and orthogonal needle mount.

The accessories include a cased pair of dip needles, a cased pair of bar magnets, a wood holder for remagnetizing the needles, a brass cover for an orthogonal calibration needle, and a fitted mahogany carrying case.

This is the instrument a surveyor would want. Surveys of magnetic declination (the difference between magnetic and geographic North) and magnetic dip (the angle at which the magnetic field of earth differs from horizontal) are invaluable in the everyday business of land-surveying. Magnetic anomalies (places where the magnetic angles depart from customary for the area) often reveal ore deposits.

Museum Hours: Tuesday - Saturday 10 to 5
Thursdays 10 am to  8pm 
Closed Major Holidays
Library Hours: Monday - Friday 9 to 4:30

Admission: $7 Adults; $5 Students & Seniors; Children 3 and under are FREE!

© The Bakken Updated: April 6, 2007