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De Magnete
''De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure'' (''On the Magnet and Magnetic Bodies, and on That Great Magnet the Earth'') 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. Contents In ''De Magnete'', Gilbert described many of his experiments with his model Earth called the '' terrella''. Gilbert made the claim that gravity was due to the same force and he believed that this held the Moon in orbit around the Earth. The work then considered static electricity produced by amber. Amber is called ''elektron'' in Greek, and ''electrum'' in Latin, so Gilbert decided to refer to the phenomenon by the adjective ''electricus''. Summary ''De Magnete'' consists of six books. Book 1 Historical survey of magnetism and theory of Earth's magnetism. The lodestone in antiq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Gilbert (astronomer)
William Gilbert (; 24 May 1544? – 30 November 1603), also known as Gilberd, was an English physician, physicist and natural philosophy, natural philosopher. He passionately rejected both the prevailing Aristotelian philosophy and the Scholasticism, Scholastic method of university teaching. He is remembered today largely for his book ''De Magnete'' (1600). A unit of magnetomotive force, also known as magnetic scalar potential, magnetic potential, was named the ''Gilbert (unit), Gilbert'' in his honour; it has now been superseded by the Ampere-turn. Life and work Gilbert was born in Colchester to Jerome Gilberd, a borough Recorder (judge), recorder. He was educated at St John's College, Cambridge. After gaining his Doctor of Medicine, MD from Cambridge in 1569, and a short spell as bursar of St John's College, he left to practice medicine in London, and he travelled on the continent. In 1573, he was elected a Fellow of the Royal College of Physicians. In 1600, he was elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic against the fixed stars, background of stars – specifically the Zodiac constellations. The planets of the Solar System can also be seen along the ecliptic, because their orbital planes are very close to Earth's. The Moon's orbital plane is also similar to Earth's; the ecliptic is so named because the ancients noted that eclipses only occur when the Moon is crossing it. The ecliptic is an important Plane of reference, reference plane and is the basis of the ecliptic coordinate system. Ancient scientists were able to calculate Earth's axial tilt by comparing the ecliptic plane to that of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Project Gutenberg
Project Gutenberg (PG) is a volunteer effort to digitize and archive cultural works, as well as to "encourage the creation and distribution of eBooks." It was founded in 1971 by American writer Michael S. Hart and is the oldest digital library. Most of the items in its collection are the full texts of books or individual stories in the public domain. All files can be accessed for free under an open format layout, available on almost any computer. , Project Gutenberg had reached over 75,999 items in its collection of free eBooks. The releases are available in plain text as well as other formats, such as HTML, PDF, EPUB, MOBI, and Plucker wherever possible. Most releases are in the English language, but many non-English works are also available. There are multiple affiliated projects that provide additional content, including region- and language-specific works. Project Gutenberg is closely affiliated with Distributed Proofreaders, an Internet-based community for proofr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Of Maricourt
Petrus Peregrinus de Maricourt (Latin), Pierre Pelerin de Maricourt (French), or Peter Peregrinus of Maricourt (fl. 1269), was a French mathematician, physicist, and writer who conducted experiments on magnetism and wrote the first extant treatise describing the properties of magnets. His work is particularly noted for containing the earliest detailed discussion of freely pivoting compass needles, a fundamental component of the dry compass soon to appear in medieval navigation. He also wrote a treatise on the construction and use of a universal astrolabe. Peregrinus's text on the magnet is entitled in many of the manuscripts of it ''Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt, militem, de magnete'' ("Letter of Peter Peregrinus of Maricourt to Sygerus of Foucaucourt, Soldier, on the Magnet") but it is more commonly known by its short title, ''Epistola de magnete'' ("Letter on the Magnet"). The letter is addressed to an otherwise unknown Picard countryman named S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copernican Heliocentrism
Copernican heliocentrism is the astronomical scientific modeling, model developed by Nicolaus Copernicus and published in 1543. This model positioned the Sun at the center of the Universe, motionless, with Earth and the other planets orbiting around it in circular trajectory, paths, modified by epicycles, and at uniform speeds. The Copernican model displaced the geocentric model of Ptolemy that had prevailed for centuries, which had placed Earth at the center of the Universe. Although he had circulated an outline of his own heliocentric theory to colleagues sometime before 1514, he did not decide to publish it until he was urged to do so later by his pupil Rheticus. Copernicus's challenge was to present a practical alternative to the Ptolemaic model by more elegantly and accurately determining the length of a solar year while preserving the Pythagoreanism, metaphysical implications of a mathematically ordered cosmos. Thus, his heliocentric model retained several of the Ptolemaic el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axial Precession
In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orbit would show axial parallelism. In particular, axial precession can refer to the gradual shift in the orientation of Earth's axis of rotation in a cycle of approximately 26,000 years.Hohenkerk, C.Y., Yallop, B.D., Smith, C.A., & Sinclair, A.T. "Celestial Reference Systems" in Seidelmann, P.K. (ed.) ''Explanatory Supplement to the Astronomical Almanac''. Sausalito: University Science Books. p. 99. This is similar to the precession of a spinning top, with the axis tracing out a pair of cones joined at their apices. The term "precession" typically refers only to this largest part of the motion; other changes in the alignment of Earth's axis— nutation and polar motion—are much smaller in magnitude. Earth's precession was historically called the precession of the equinoxes, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primum Mobile
In classical, medieval, and Renaissance astronomy, the Primum Mobile (Latin: "first movable") was the outermost moving sphere in the geocentric model of the universe. The concept was introduced by Ptolemy to account for the apparent daily motion of the heavens around the Earth, producing the east-to-west rising and setting of the sun and stars, and reached Western Europe via Avicenna. Appearance and rotation The Ptolemaic system presented a view of the universe in which apparent motion was taken for real – a viewpoint still maintained in common speech through such everyday terms as ''moonrise'' and ''sunset''. Rotation of the Earth on its polar axis – as seen in a heliocentric solar system, which (while anticipated by Aristarchus) was not to be widely accepted until well after Copernicus – leads to what earlier astronomers saw as the real movement of all the heavenly bodies around the Earth every 24 hours. Astronomers believed that the seven naked-eye planets (includi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heraclides Ponticus
Heraclides Ponticus ( ''Herakleides''; c. 390 BC – c. 310 BC) was a Greek philosopher and astronomer who was born in Heraclea Pontica, now Karadeniz Ereğli, Turkey, and migrated to Athens. He is best remembered for proposing that the Earth rotates on its axis, from west to east, once every 24 hours. He is also hailed as the originator of the heliocentric theory; although this is disputed. Life Heraclides' father was Euthyphron, a wealthy nobleman who sent his son to study at the Platonic Academy in Athens under its founder Plato and under his successor Speusippus. According to the ''Suda'', Plato, on his departure for Sicily in 361/360 BC, left the Academy in the charge of Heraclides. Heraclides was nearly elected successor to Speusippus as head of the academy in 339/338 BC, but narrowly lost to Xenocrates. All of Heraclides' writings have been lost; only a few fragments remain. Like the Pythagoreans Hicetas and Ecphantus, Heraclides proposed that the apparent daily mot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth's Rotation
Earth's rotation or Earth's spin is the rotation of planet Earth around its own Rotation around a fixed axis, axis, as well as changes in the orientation (geometry), orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Polaris, Earth turns counterclockwise. The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where Earth's axis of rotation meets its surface. This point is distinct from Earth's north magnetic pole. The South Pole is the other point where Earth's axis of rotation intersects its surface, in Antarctica. Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes and 4 seconds with respect to other distant stars (#Stellar and sidereal day, see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal acceleration, tidal effects ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dip Circle
Dip circles (also known as ''dip needles or inclination compasses'') are used to measure the angle between the horizon and the Earth's magnetic field (the Magnetic dip, dip angle). They were used in surveying, mining and prospecting as well as for the demonstration and study of magnetism. Uses Dip circles typically consist of a magnetised needle swinging freely vertically within a case. The needle will dip to follow the lines of Earth's magnetic field. As the dip angle varies by latitude (0° at the equator and 90° at the poles), a dip circle can be used to determine latitude when compared against a chart of dip angles. As the variation is not constant, this is not an exact measurement. Dip circles can also be used in locate ore, and they were the first scientific instrument to be used for this purpose. They were used to find magnetite in Sweden in the Middle Ages, and have been used extensively in iron mining. They were still in use in the 1930s, but modern Magnetometer, ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latitude
In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at the south pole to 90° at the north pole, with 0° at the Equator. Parallel (latitude), Lines of constant latitude, or ''parallels'', run east-west as circles parallel to the equator. Latitude and longitude are used together as a coordinate pair to specify a location on the surface of the Earth. On its own, the term "latitude" normally refers to the ''geodetic latitude'' as defined below. Briefly, the geodetic latitude of a point is the angle formed between the vector perpendicular (or ''Normal (geometry), normal'') to the ellipsoidal surface from the point, and the equatorial plane, plane of the equator. Background Two levels of abstraction are employed in the definitions of latitude and longitude. In the first step the physical surface i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Dip
Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by Earth's magnetic field, Earth's magnetic field lines. This angle varies at different points on Earth's surface. Positive values of inclination indicate that the magnetic field of Earth is pointing downward, into 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. Dip angle was discovered by the German engineer Georg Hartmann in 1544. A method of measuring it with a dip circle was described by Robert Norman in England in 1581. Explanation Magnetic dip results from the tendency of a magnet to align itself with lines of magnetic field. As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
