Aurora Borealis is a luminous meteoric phenomenon appearing in the north, most frequently in high latitudes, the corresponding phenomenon in the southern hemisphere being called AuroraAustralia, and both being also called Polar Light, Streamers, etc. The northern aurora has been far the most observed and studied. It usually manifests itself by streams of light ascending towards the zenith from a dusky line of cloud or haze a few degrees above the horizon, and stretching from the north towards the west and east, so as to form an arc with its ends on the horizon, and its different parts and rays are constantly in motion. Sometimes it appears in detached places; at other times it almost covers the whole sky. It assumes many shapes and a variety of colours, from a pale red or yellow to a deep red or blood colour; and in the northern latitudes serves to illuminate the earth and cheer the gloom of the long winter nights. Research Aurora Borealis
Castor is a star (Alpha Geminorum) of magnitude 1.6, the fainter star of the zodiacal constellationGemini, or the Twins. In 1719 it was discovered to be a visual binary star, with components of magnitudes 2.8 and 2.0 separated by 6 seconds of arc and revolving around each other in about 350 years. Each of these components has been found to be a spectroscopic binary. In addition, a faint companion, separated from the other two by 72 sec of arc, has been discovered. This star is also a spectroscopic binary, the two components of which revolve around each other in about one day. Hence, the entire system of the star Castor contains at least six stars. Its distance is about 45 light- years from the earth. Research Castor
A dam is a bank or construction of stone, earth, or wood etc across a stream or river for the purpose of keeping back the current to give it increased head, for holding back supplies of water, for floodinglands, for rendering the stream above the dam navigable by increased depth, and for generating electricity. Its material and construction will depend on its situation and the amount of pressure it has to bear. For streams which are broad and deep strong materials are required, usually stone masonry bound in hydraulic cement and a strong framework of metal or timber. The common forms of a dam are either a straight line crossing the stream transversely, or one or two straight lines traversing it diagonally, or an arc with its convex side towards the current. Research Dam
In astronomy, nutation is a slight 'nodding' of the Earth in space, caused by the varying gravitational pulls of the Sun and Moon. Nutation changes the angle of the Earth's axial tilt by about nine seconds of arc to either side of its mean position, a complete cycle taking just over 18.5 years. Research Nutation
The radian is the SI unit (symbolrad) of plane angles, an alternative unit to the degree. It is the angle at the centre of a circle when the centre is joined to the two ends of an arc equal in length to the radius of the circle. There are 2 pi (approximately 6.284) radians in a full circle (360 degrees). One radian is approximately 57 degrees, and 1 degree is pi/180 or approximately 0.0175 radians. Radians are commonly used to specify angles in polar co-ordinates. Research Radian
Originally sine was another word to describe a gulf or a bay, as in 'The Persian Sine', today its use is more limited to its trigonometry variation which describes the straight line drawn from one extremity of an arc perpendicular to the diameter passing through the other extremity. Research Sine
The hazel is a shrub and sometimes small tree of the genus Corylus, sub-family Corylaceae, family Betulaceae, found in Europe, North Africa, Asia, and North America.. The leaves are roundish-cordate, alternate and shortly petiolate. The bark is reddish-brown and smooth. The plant is monoecious, the male flowers are clustered in pendulous catkins, the female flowers are arranged in erect, short, bud-like spikes with protruding red styles. The fruit is a hard, brown, rounded nut (filbert), enclosed by an irregularly lobed green involucre.
The European hazel (Corylus Avellana) produces the nuts called filberts, and grows best in a tolerably dry soil. It bears male and female flowers, the former composing cylindrical catkins. The hazel-nut oil is little inferior in flavour to that of almonds. Hazel branches form excellent walking-sticks, fishing-rods, etc, and the wood produces good charcoal, often employed by painters.
The American hazel (Corylus. americana) very much resembles the European. The roots are used by cabinet-makers for veneering; and in Italy the chips were formerly sometimes put into turbid wine for the purpose of fining it.
The witch hazel or wych hazel, Hamamelis virginica, is a shrub or small tree of a different natural order, the Hamamelidaceae. It is a native of the United States, and healing properties have long been ascribed to it both by the Indians and the settlers. A liquid prepared from it is said to be useful as an application to wounds, stanching the bleeding and promoting healing, being applied also to bruises, sprains, bleeding piles, in internal bleeding, etc. There arc several officinal preparations of the witch-hazel, especially a fluid extract and a tincture. The former American patent medicine, Pond's Extract, owed its chief properties to the witch-hazel. Research Hazel
Alexis Claude Clairaut was a French mathematician. He was born in 1713 at Paris and died in 1765. In his eleventh year he composed a treatise on the four curves of the third order, which, with his subsequent Recherches sur les Courbes a double Courbure, 1731, procured him a seat in the Academy at the age of eighteen. He accompanied Maupertuis to Lapland, to assist in measuring an arc of the meridian, and obtained the materials for his work Sur la Figure de la Terre. In 1752 he published his Theorie de la Lune, and in 1759 calculated the perihelion of Halley's comet. Research Alexis Clairaut
Charles VII (Charles The Victorious) was king of France. He was born in 1403 and died in 1461. He was crowned in 1422 after the death of his father, Charles VI, in spite of the treaty of Troyes which gave Henry V of England claim to the throne following his conquest of the country. He made little progress against the English until the advent of Joan of Arc in 1429.
Charles VII was Emperor of Germany. He was born in 1697 and died in 1745. He was the son of Maximilian Emanuel, elector of Bavaria. On the death of Charles VI of Germany he refused to acknowledge Maria Theresa as heiress and in support of his own claims he invaded Austria with an army, took Prague and was crowned King of Bohemia and in 1742 was elected Emperor. But fortune soon deserted him. The armies of Maria Theresa reconquered all Upper Austria, and overwhelmed Bavaria. Charles fled to Frankfurt, and returning to Munich in 1744, died there the following year. Research Charles VII
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Aurora Borealis
