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The earliest Chinese magnetic compasses were possibly used to order and harmonize buildings by the geomantic principles of feng shui. These early compasses were made with lodestone, a form of the mineral magnetite that is a naturally occurring magnet and aligns itself with the Earth's magnetic field. [10]
A modern military compass, with included sight device for aligning. A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with magnetic north.
A beam compass and a regular compass Using a compass A compass with an extension accessory for larger circles A bow compass capable of drawing the smallest possible circles. A compass, also commonly known as a pair of compasses, is a technical drawing instrument that can be used for inscribing circles or arcs.
According to Needham, the Chinese in the Song dynasty and continuing Yuan dynasty did make use of a dry compass. [17] The dry compass used in China was a dry suspension compass, a wooden frame crafted in the shape of a turtle hung upside down by a board, with the lodestone sealed in by wax, and if rotated, the needle at the tail would always ...
Rulers used in technical drawing are usually made of polystyrene. It is used for drawing lines and connecting points. Rulers come in two types according to the design of their edge. A ruler with a straight edge can be used with lead pencils and felt pens, whereas when a technical pen is used the edge must be grooved to prevent the spread of the ...
The compass may or may not collapse (i.e. fold after being taken off the page, erasing its 'stored' radius). Lines and circles constructed have infinite precision and zero width. Actual compasses do not collapse and modern geometric constructions often use this feature. A 'collapsing compass' would appear to be a less powerful instrument.
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Floating-card compass with prismatic sight (bearing 220° through eyepiece). The marine hand compass, or hand bearing compass|hand-bearing compass as it is termed in nautical use, has been used by small-boat or inshore sailors since at least the 1920s to keep a running course or to record precise bearings to landmarks on shore in order to determine position via the resection technique.