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Dip circles (also ''dip needles'') are used to measure the angle between the horizon and the
Earth's magnetic field
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic ...
mining
Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic ...
and
prospecting
Prospecting is the first stage of the geological analysis (followed by exploration) of a territory. It is the search for minerals, fossils, precious metals, or mineral specimens. It is also known as fossicking.
Traditionally prospecting rel ...
as well as for the demonstration and study of magnetism.
Georg Hartmann first discovered dip angle in 1544, when he noticed the needle on a
compass
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 wit ...
dipped towards the north
hemisphere
Hemisphere refers to:
* A half of a sphere
As half of the Earth
* A hemisphere of Earth
** Northern Hemisphere
** Southern Hemisphere
** Eastern Hemisphere
** Western Hemisphere
** Land and water hemispheres
* A half of the (geocentric) celes ...
. Rather than explore this phenomenon, Hartmann sought ways to eliminate it. However,
Robert Norman
Robert Norman was a 16th-century-English mariner, compass builder, and hydrographer who discovered magnetic inclination, the deviation of the Earth's magnetic field from the vertical.
Work
Robert Norman is noted for ''The Newe Attractive'' ...
around 1576 investigated dip angle further and in 1581 described in print a device to measure this phenomenon.Norman, Robert; Borough, William. (1581). ''The newe attractiue, containyng a short discourse of the magnes or lodestone, and amongst other his vertues, of a newe discouered secret and subtill propertie, concernyng the declinyng of the needle, touched therewith vnder the plaine of the horizon. Now first founde out by Robert Norman. Herevnto are annexed certaine necessarie rules for the art of nauigation, by the same R. N.'' London: Ihon Kyngston for Richard Ballard WorldCat record. OCLC: 181712334.
Early dip circles were not accurate and gave poor results. Over the next 300 years many improvements were made, including reducing the
friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative lateral motion of ...
between the needle and its pivot and encasing the circle in glass. Between the late 18th century and late 19th century the design approached its peak. Improvements which made the dip circle a practical aid for polar navigation were made by Robert Were Fox FRS, who developed in the 1830s the first dip circle that could be used on board a moving ship. Another important improvement to the instrument was developed in the 1830s by the
Dublin
Dublin (; , or ) is the capital and largest city of Ireland. On a bay at the mouth of the River Liffey, it is in the province of Leinster, bordered on the south by the Dublin Mountains, a part of the Wicklow Mountains range. At the 2016 c ...
physicist Humphrey Lloyd, who devised a way of attaching a magnetic needle at right-angles to the dip needle in order to measure the intensity of force (by seeing the extent to which the right-angle needle deflected the dip-needle).
By
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
the most advanced dip circles were being made. With the development of electronic systems dip circles became obsolete.
See also
*
Magnetic dip
Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by the Earth's magnetic field lines. This angle varies at different points on the Earth's surface. Positive values of inclination indicate that the magnetic fi ...