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Cammenga lensatic compass The M-1950 U.S. military lensatic field compass with self-luminous lighting (designated the Model 3H by Cammenga) is fitted with self-luminous tritium vial lighting. Under U.S. military specification (MIL-SPEC) performance criteria, ten pre-production samples of the M-1950 are required to meet a battery of performance ...
Classic geological compass (Brunton), sideview Classic geological compass (Brunton), topview. There are a number of different specialized magnetic compasses used by geologists to measure orientation of geological structures, as they map in the field, to analyze and document the geometry of bedding planes, joints, and/or metamorphic foliations and lineations.
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Model of a lodestone compass from Han dynasty. Some claims state that the first compasses in ancient Han dynasty China were made of lodestone, a naturally magnetized ore of iron. [2] [16] The earliest mention of a needle's attraction appears in a work composed between 20 and 100 AD, the Lunheng (Balanced Inquiries): "A lodestone attracts a needle."
A beam compass is a compass with a beam and sliding sockets or cursors for drawing and dividing circles larger than those made by a regular pair of compasses. [1] The instrument can be as a whole, or made on the spot with individual sockets (called trammel points) and any suitable beam.
It is also curious and questionable that no one mentioned the use of the Chinese dry suspension compass as early as the 12th century, and blatantly wrote that the only compass known in China before European influence was the wet compass placed in a bowl of water. To this I say: hogwash.--
The Earth's axis of rotation remains effectively stationary throughout the year. Thus, with knowledge of the current time and geographical position in the form of latitude and longitude, which are set on the instrument using dials, an astrocompass can be sighted onto any astronomical object with a known position to give an extremely accurate reading.
Magnetic dip causes the compass to dip upward or downward depending on the latitude. Illustration of magnetic dip from Norman's book, The Newe Attractive Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by Earth's magnetic field lines.