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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.
Robert Norman is noted for The Newe Attractive, a pamphlet published in 1581 [1] describing the lodestone (magnet) and practical aspects of navigation. More importantly, it included Norman's measurement of magnetic dip, the incline at an angle from the horizon by a compass needle discovered by Georg Hartmann in 1544. This effect is caused by the Earth's magnetic field not running parallel to the planet's surface. Norman demonstrated magnetic dip by creating a compass needle that pivoted on a horizontal axis. The needle tilted at a steep angle relative to the horizon line.
Magnetic inclination and local variations were known before Robert Norman, but his pamphlet had a greater influence than the earlier work[ citation needed ].
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. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers.
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely.
Timeline of electromagnetism and classical optics lists, within the history of electromagnetism, the associated theories, technology, and events.
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in the Earth's outer core: these convection currents are caused by heat escaping from the core, a natural process called a geodynamo. The magnitude of the Earth's magnetic field at its surface ranges from 25 to 65 μT. As an approximation, it is represented by a field of a magnetic dipole currently tilted at an angle of about 11 degrees with respect to Earth's rotational axis, as if there were an enormous bar magnet placed at that angle through the center of the Earth. The North geomagnetic pole actually represents the South pole of the Earth's magnetic field, and conversely the South geomagnetic pole corresponds to the north pole of Earth's magnetic field. As of 2015, the North geomagnetic pole was located on Ellesmere Island, Nunavut, Canada.
A terrella is a small magnetised model ball representing the Earth, that is thought to have been invented by the English physician William Gilbert while investigating magnetism, and further developed 300 years later by the Norwegian scientist and explorer Kristian Birkeland, while investigating the aurora.
Magnetic declination, or magnetic variation, is the angle on the horizontal plane between magnetic north and true north. This angle varies depending on position on the Earth's surface and changes over time.
A (geographic) meridian is the half of an imaginary great circle on the Earth's surface, a coordinate line terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of the Equator. Each meridian is perpendicular to all circles of latitude. Meridians are half of a great circle on the Earth's surface. The length of a meridian on a modern ellipsoid model of the earth has been estimated at 20,003.93 km.
Dip circles are used to measure the angle between the horizon and the Earth's magnetic field. They were used in surveying, mining and prospecting as well as for the demonstration and study of magnetism.
Magnetic deviation is the error induced in a compass by local magnetic fields, which must be allowed for, along with magnetic declination, if accurate bearings are to be calculated.
De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure is a scientific work published in 1600 by the English physician and scientist William Gilbert. A highly influential and successful book, it exerted an immediate influence on many contemporary writers, including Francis Godwin and Mark Ridley.
An astrocompass is a navigational tool for determining the direction of true north through the positions of various astronomical bodies.
A Brunton compass, properly known as the Brunton Pocket Transit, is a precision compass made by Brunton, Inc. of Riverton, Wyoming. The instrument was patented in 1894 by a Canadian-born geologist named David W. Brunton. Unlike most modern compasses, the Brunton Pocket Transit utilizes magnetic induction damping rather than fluid to damp needle oscillation. Although Brunton, Inc. makes many other types of magnetic compasses, the Brunton Pocket Transit is a specialized instrument used widely by those needing to make accurate navigational and slope-angle measurements in the field. Users are primarily geologists, but archaeologists, environmental engineers, mining engineers and surveyors also make use of the Brunton's capabilities. The United States Army has adopted the Pocket Transit as the M2 Compass for use by crew-served artillery.
Space physics, also known as solar-terrestrial physics or space-plasma physics, is the study of plasmas as they occur naturally in the Earth's upper atmosphere (aeronomy) and within the Solar System. As such, it encompasses a far-ranging number of topics, such as heliophysics which includes the solar physics of the Sun: the solar wind, planetary magnetospheres and ionospheres, auroras, cosmic rays, and synchrotron radiation. Space physics is a fundamental part of the study of space weather and has important implications in not only to understanding the universe, but also for practical everyday life, including the operations of communications and weather satellites.
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 field of the Earth is pointing downward, into the Earth, at the point of measurement, and negative values indicate that it is pointing upward. The dip angle is in principle the angle made by the needle of a vertically held compass, though in practice ordinary compass needles may be weighted against dip or may be unable to move freely in the correct plane. The value can be measured more reliably with a special instrument typically known as a dip circle.
Henry Gellibrand (1597–1637) was an English mathematician. He is known for his work on the Earth's magnetic field. He discovered that magnetic declination – the angle of dip of a compass needle – is not constant but changes over time. He announced this in 1635, relying on previous observations by others, which had not yet been correctly interpreted.
The north magnetic pole is a point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downward. There is only one location where this occurs, near the geographic north pole. The geomagnetic north pole, a related point, is the pole of an ideal dipole model of the Earth's magnetic field that most closely fits the Earth's actual magnetic field.
The year 1581 in science and technology included the following notable events.
The history of geomagnetism is concerned with the history of the study of Earth's magnetic field. It encompasses the history of navigation using compasses, studies of the prehistoric magnetic field, and applications to plate tectonics.
A compass is a magnetometer used for navigation and orientation that shows direction in regards to the geographic cardinal points. For the structure of the compass, it will show the diagram called compass rose in showing the 4 main directions: East (E), South (S), West (W) and North (N). The angle increases in the clockwise position. North corresponds to 0°, so east is 90°, south is 180° and west is 270°.
Burt's solar compass or astronomical compass is a surveying instrument that makes use of the sun's direction instead of magnetism. William Austin Burt invented his solar compass in 1835. The solar compass works on the principle that the direction to the sun at a specified time can be calculated if the position of the observer on the surface of the Earth is known, to a similar precision. The direction can be described in terms of the angle of the sun relative to the axis of rotation of the planet.
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