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Knight's Mechanical Encyclopedia (ed. Knight), A. (search)
t, where the Swiss defeated Charles the Bold, 1476. Arrastra. Ar-ras′tra. One form of machine for comminuting ore. The name is derived from the Spanish word meaning to drag, and is indicative of the machine. It consists of a pan in which the ore is placed, and a vertical rotating post, to whose radial arms are attached thongs by which blocks or mullers are dragged over the ore in the pan. They are very common in Mexico, where they operate upon argentiferous ores, and, according to Humboldt, do excellent work. They have been superseded to some extent by other forms of grinding-mills. See amalgamating mills; ore-stamp; ore-crusher. Three arrastras are patented in the United States. Fig. 367 has the distinct arrastra characteristics, and is designed for the reduction of precious metals from ores and tailings: it has a east-iron pan provided with two flanges, placed on opposite sides, and terminating in a ball-pivot, which rests in a cup-shaped bearing on the frame, by whi
Knight's Mechanical Encyclopedia (ed. Knight), G. (search)
en was first discovered by Dr. Priestley in 1774; he obtained it by heating red oxide of mercury, and called it dephlogisticated air. Scheele and Lavoisier a year or two later made the same discovery, independently of the English inventor, as Humboldt thinks. It was termed empyreal air by Scheele; vital air by Cordorcet. The name oxygen was given to it by Lavoisier. Black and Cavendish, in 1766, showed that carbonic acid (fixed air) and hydrogen gas (combustible air) are specifically dis anciently used in China for astronomical purposes, but this people did not excel in dialing. A measurement of the length of the solstitial shadow, made by Tschea-Kung, at Loyang, on the Yellow River, 1200 B. C., was found by Laplace (quoted by Humboldt in Cosmos, Val. 11. p. 1151 to accord perfectly with the present accepted theory of the change in the obliquity of the ecliptic. The sun-dial and the gnomon, with the division of the day into twelve parts, were received by the Greeks from the
Knight's Mechanical Encyclopedia (ed. Knight), I. (search)
At least one natural ice-house has been discovered on Mount Etna, where a vast deposit of snow, covered by a mass of ashes and lava, has been preserved for untold ages. The highest natural temperature authentically recorded was at Bagdad, in 1819, when the themometer in the shade indicated 120° Fah. On the west coast of Africa the heat is nearly as great. The men employed in the English expedition to Abyssinia think that Aden is the hottest hole on earth. Burckhardt, in Egypt, and Humboldt, in South America, observed 117° Fah. in the shade. About—70° is the lowest temperature observed by our Arctic navigators. Natterer, a German chemist, obtained—220° Fah. Faraday obtained—166° Fah. Neither succeeded in freezing pure alcohol or ether. Fig. 2642 is a sectional view of an ice-house for brewers and butchers. It has an ice-chamber B and cooling-vault A, provided with one or more ventilators I. Ice-leveler. Ice-lev′el-er. An implement for leveling the surfac
Knight's Mechanical Encyclopedia (ed. Knight), L. (search)
dships, and carried up to any convenient hight, when Reid's log. it is curved downward and united to the leg of an inverted siphon containing mercury. When the ship is making headway, the water which enters the tube through an aperture near its lower end rises, forcing up the mercury, which indicates the ship's speed on a suitable register. By turning the tube so that the aperture forms a certain angle with the keel, the ship's draft may be ascertained. In reference to this subject Humboldt says, — It has frequently been asserted that the use of the log for measuring a ship's way dates back only to the end of the sixteenth or beginning of the seventeenth century, the year 1607 being usually assigned as the period when the first mention of it occurs. Navarrete says that it was used on board English ships in 1577, and that in Magellan's time the ship's speed was estimated by the eye. On the contrary, Pigafetta, a companion of Magellan, speaks of the log, la catena a poppa
Knight's Mechanical Encyclopedia (ed. Knight), M. (search)
ia to Europe. The Chinese annals show that it was used by them nearly 3,000 years ago, — first on land, then on water. Humboldt remarks the singular fact. It was used at sea by the Chinese as early as the era of Alexander the Great. No mention is region of storms which surrounds the Cape and enter upon the waters, usually more placid, of the great Indian Ocean. Humboldt says: I have shown elsewhere how a knowledge of the period at which Vespucci was named Piloto Mayor would alone beor injustice toward the Admiral. Even Copernicus contributed to the erroneously obtained celebrity of Vespucci. To Humboldt we are indebted for the graphic representations of complex natural phenomena by means of lines on maps, such as the isote public buildings should be directed. It thus appears that the compass was first used by land travelers, which, as Humboldt remarks, is a singular fact. It was, however, used on board vessels in the Chinese seas in the fourth century A. D. and
Knight's Mechanical Encyclopedia (ed. Knight), R. (search)
year. In Kazan it rains 90 days in the year. In Siberia it rains 60 days in the year. On the Dofrefelds of Norway it rains and mists nearly continually an aggregate of 82 inches per annum; about equal to Bombay, Havana, Sierra Leone. Humboldt estimates the average rainfall at the equator, 96 inches; at latitude 19° 80 inches; at latitude 45°, 29 inches at latitude 60°, 17 inches. According to Professor Thomson, the average number of days on which rain falls is, between latitudes 1eet wide, faced with flags covered with bitumen, and had milestones. The shore road was built on an embankment, with a clay parapet on each side, and shade-trees. It was supported by piles, in places. Every five miles there was a post-house. Humboldt declares the road magnificent. We learn from the venerable Bede (A. D. 700) that the Roman roads of England were built at various periods in the second, third, and fourth centuries; the people, criminals, and the Roman soldiery being employed
Knight's Mechanical Encyclopedia (ed. Knight), S. (search)
of this kind, mentioned by Kirchen, is 330 feet long, and is said to have been built A. D. 65. Bamboo-bridges exist in Japan. One over the Fujikaira River is stated to be about 100 feet above the river; its span being 60 and width 4 feet. Humboldt refers to the bridges of ropes used by the native Americans, and called cimppacha, from cimppa, ropes; and chaca, a bridge. The ropes of one, referred to by this distinguished German, were 3 or 4 inches in diameter, and made from the fibrous roots of the American agave. They are anchored by fastening on the shore to the trunks of trees, and the track is formed of bamboos laid transversely. They are subject to dangerous lateral swaying, and Humboldt advises to cross them on a run, keeping the body well forward, and in single file. He says that a guide and traveler walking at different rates, especially if the latter stop and grasp the balustrade-ropes, will throw the bridge into convulsions. The road between Quito and Lima cross
Knight's Mechanical Encyclopedia (ed. Knight), T. (search)
spective hands. Fortunately he tried the experiment with a concave and convex glass, which gave the wonderful effect now so familiar. They were fitted in a wooden tube, and made the first telescope ever used in the world, says Descartes. The inventor was a suspicious character, and tried to keep the invention secret even on his deathbed. But his brother and some few others had seen it, and were able to follow the track, which they opened to the world, and which was followed by Galilco. Humboldt says:— The accidental discovery of the space-penetrating power of the telescope was first made in Holland, probably as early as the close of the year 1608. According to the latest documentary investigations, this great invention may be claimed by Hans Lippershey (or Laprey), a native of Wesel, and spectacle-maker at Middelburg; Jacob Adriansz, also called Metius, who is said to have made burning-glasses of ice; and Zacharias Jansen. Lippershey, on the 2d of October, 1608, offered
Knight's Mechanical Encyclopedia (ed. Knight), W. (search)
ity of Tlascala in Mexico, was furnished with abundance of baths and fountains. Every house in Zempoloa had water. Tezcuco had an aqueduct from which every house was supplied by a pipe, as in modern cities. Cortez, in his first letter to Charles V., mentions the spring of Amilco, near Churubusco, of which the water was conveyed to the city of Mexico in two large pipes, molded and hard as stone, but the waters never ran but in one at the same time. The Spaniards destroyed it, of course. Humboldt saw the remains of it, and says it was inferior to the aqueduct of Tezcuco. The inca Garcilasso de la Vega was born in 1539 at Cusco, in Peru, about eight years after the Spanish invasion. His mother was a native princess, his father a Spaniard. He writes as follows of the Peruvian aqueducts:— The seventh inca, Viracocha, made an aqueduct 12 feet in depth and 120 leagues in length; the source or head of it arose from certain springs on the top of a high mountain between Parcu