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The counterpoise weights of this apparatus enable the constant acceleration of speed caused by gravity in a falling body to be shown and measured within the space of a few feet more accurately and satisfactorily than could be done by the fall of a weight not thus counterpoised from a considerable hight. It may also be employed to illustrate the laws of retarded motion, impact of bodies, and resistance of fluids, as well as other phenomena of a similar nature. Alhazen the Saracen, A. D. 1100, in his Book of the balance of wisdom, considered the subject of gravity, and asserted that it diminished with the distance. It was reserved for Newton to determine that it decreased as the square of the distance. Alhazen determined correctly the relation between the velocities, spaces, and times of falling bodies. The University of Cordova was the intellectual center of Europe in his day. The Khalif Alkamen's library was so large that its catalogue filled 40 volumes. The people of Cordov
d by a bank, and intended to circulate as currency. Chinese paper money was issued about A. D. 1100. Blest paper credit, as Byron says. Genghis Khan issued paper money, but all his power could not of the atmosphere at different hights was known before Torricelli. Alhazen the Saracen, A. D. 1100, was aware that the atmosphere decreases in density with increase of hight, and therefrom explainich both eyes may be applied. Alhazen, the Saracen, who flourished in Egypt and in Spain A. D. 1100, was the first to correct the Greek misconception as to the nature of vision, showing that the ray I. to Edward VI., took their coronation oath, was bound in oak boards, nearly an inch thick, in 1100. Velvet was the covering in the fourteenth century. Silk soon after. Vellum in the fifteenthvangelists, on which the English kings took their coronation oath, was bound in oak boards, A. D. 1100. Hog-skin and leather were used in the fifteenth century. Calf in 1550. Silk and velvet
by Leonardo da Vinci, in 1500, as an imitation of the mechanical structure of the eye. The theory of optical sensation was laid down by Alhazen the Saracen, A. D. 1100. See binocular glasses. Baptista Porta, in 1589, mentions it in his book on Natural magic. Sir Isaac Newton remodeled it, 1700. Daguerre, in 1839, rendered ckets. The word now includes a frame with gas branches, though the latter is technically a gasalier. A chandelier in the palace of the Khalif of Cordova, A. D. 1100, contained 1,084 lamps. Cordova was then the intellectual center of Europe, and the royal dwellings of Germany, France, and England were like stables. 2. An obn time in the evening. William J. introduced this law into England in 1068, and fixed the ignitegium at seven in the evening. The law was abolished by Henry I. in 1100. The curfew-bell also answered as a vesper-bell, calling the people to prayers. Pope John XXIII. ordered three Ave-Marias to be repeated at the hearing of the
The stove consumes the gas in a separate chamber from that containing the pipes to be heated; air to support combustion is allowed to enter, and the heated fumes escape through a series of narrow slots into an air-tight chamber having a damper on the top and containing a series of vertical reverting pipes through which passes the blast to be heated. As the highly heated fumes will not again ignite without a fresh supply of oxygen, the cast-iron blast-pipes remain uninjured under a heat of 1100° or 1200°. An auxiliary fireplace for burning coal is shown attached to the hot-blast stove. From this fireplace a flue conducts the flame, smoke, and gases from the blast-furnace into the chamber where the combustion is completed. Attached to the end of this fireplace, and connected with flues at the furnacetop, is a branch gas-pipe with a small steam-jet placed near its orifice to create a partial vacuum. This draws the gases down from the furnace-top and forces them into the stoves,
ptics. Glass balls, called burning spheres, were sold in Athens before the Christian era. Their magnifying power was mentioned by the Roman philosopher Seneca, and by Porta of Naples in his Magia Naturalis, published in 1590. Alhazen, A. D. 1100, was the first to correct the popular error as to the nature of vision, showing that the rays came from the object and did not issue from the eye, as had been previously supposed. He determined that the retina is the seat of vision, and that impr The ancients knew, — 1. That the rays of light were projected in straight lines. 2. That the angle of incidence is equal to the angle of reflection. These were their only contributions to the science of optics. Alhazen, about A. D. 1100, shed a flood of light on the subject. Silver is the most powerful reflector, absorbing but 9 per cent of the light (speculum-metal absorbs 37 per cent of the rays), and for this reason, as well as its durability, was largely employed by the an
th of lenses suited for remedying imperfect vision. Lehot's device consists of a white thread placed on a narrow rule covered with black velvet, and having an arrangement for indicating the points at which the thread begins and ceases to be distinctly seen when held in a certain position with respect to the eye. See also Optometer. Op′ti-cal In′stru-ments. The first ascertained optical fact was probably the propagation of light in straight lines. Alhazen the Saracen, about A. D. 1100, was the first to determine that the retina is the seat of vision, and that light comes from external objects to the eye. Before his time it had been uniformly taught that rays issued from the eye and impinged upon objects. Euclid treated the subject on that principle. Alhazen also explained the reason that we see single when we use both eyes, because of the formation of visual images on symmetrical portions of the two retinas. — Draper. He also wrote on the reflection and refraction <
the year of the Hegira 85. The oldest manuscript written on cotton paper in England is in the Bodleian collection of the British Museum, and bears date 1049. The most ancient manuscript on the same material in the Library of Paris is dated 1050. In 1085 A. D., the Christian successors of the Spanish Saracens made paper of rags instead of raw cotton, which is recognized by its yellowness and brittleness. A very early specimen of linen paper is found in a manuscript bearing the date of 1100 A. D.; though some twelve years afterward we find Roger, king of Sicily, granting a charter to some paper-makers who were then established on that island. The paper made by them was, however, probably of cotton, which was then extensively grown in Sicily. In 1151, we learn from an Arabian author that paper of a superior quality was manufactured at Xativa, in Spain, the Christian Spaniards having improved upon the processes of the Moors, from whom they learned the art, by stamping the raw mat
e, Sir Samuel Bentham's saw, in which the work was guided in an arc by a radius arm. A chair-back saw. It may be band or jig. 2. (Surgical.) A nearly circular plate of steel serrated on the edge and riveted to a wooden handle (Fig. 2502, page 1100). It is known as Hey's saw, and is used in surgical operations on the bones of the cranium, and the metacarpal and metatarsal bones. Seg′ment-shell. (Ordnance.) An elongated projectile invented by Sir W. Armstrong. The iron body is coatded by the weight of the water gives the specific gravity required. Archimedes invented the plan for determining specific gravity by displacement of water. He also enunciated the doctrine of the center of gravity. Alhazen the Saracen, A. D. 1100, improved upon the hydrometer, which had been in use in Alexandria 600 years previously. See hydrometer. Abu-r-Raihan of Kharizim, about A. D. 1000, compiled a table of specific gravities, which is quoted by Al-Khazini in his Book of the bala
James Parton, Horace Greeley, T. W. Higginson, J. S. C. Abbott, E. M. Hoppin, William Winter, Theodore Tilton, Fanny Fern, Grace Greenwood, Mrs. E. C. Stanton, Women of the age; being natives of the lives and deeds of the most prominent women of the present gentlemen, Victoria, Queen of England. (search)
vidual of striking merit, or performing any valuable service for mankind. Nevertheless, there must be in such a family real worth and real wisdom. One of the most admirable provisions among the laws of nature is that one which dooms a family of incurable fools to certain and swift extinction. The family now upon the English throne is one of the oldest in Europe. Among the mountains which divide Italy from Germany a powerful house named Welf held great possessions as long ago as the year 1100. Extending its conquests southward, it ruled some of the finest provinces of Italy, where the name was changed into Guelph, by which it has ever since been known. The Guelphs, with their impregnable castles among the mountains, drawing tribute from the fertile provinces of northern Italy and southern Germany, appear to have been for a time as wealthy and powerful a family as any in Europe of less than imperial or royal rank. It became too powerful. The Guelphs quarrelled among themselves.
28 shell; 4 Ix-inch Dahlgrens, expended 37 solid shot, 33 shell; 2 24-ponnder howitzers, expended 27 shrapnel, 18 shell; 2 12-pounder howitzers (one rifled). Casualties, 1 killed. Miami, Acting Volunteer Lieutenant Charles A. French. Battery: 1100-pounder Parrott rifle, expended 41 solid shot; 6 Ix-inch Dahlgrens, expended 76 solid shot; 1 24-ponnder howitzer. Whitehead, Acting Ensign G. W. Barrett. Battery: 1100-pounder Parrott rifle, expended 17 solid shot; 8 24-pounder howitzers. 1100-pounder Parrott rifle, expended 17 solid shot; 8 24-pounder howitzers. Commodore Hull, Acting Master Francis Josselyn. Battery: 230-pounder Parott rifles, expended 60 shell; 4 24-pounder howitzers, expended 24 shell. Ceres, Acting Master H. H. Foster. Battery: 2 20 pounder Parrott rifles (pivot). XI.—List of Ordnance left on Morris Island on the night of its evacuation, September 6, 1863. Battery Wagner. Two X-inch Columbiads (1 dismounted and broken, 1 serviceable); 1 X-inch mortar, serviceable; 2 Viii-inch shell guns (1 serviceable, 1 injured by sh
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