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150 BC (search for this): chapter 4
was visited by an august procession of philosophers during the seven centuries which separated Aristarchus from Hypatia. On the instrument, which had a plane parallel to the equator and a gnomon parallel to the earth's polar axis, Hipparchus, 150 B. C., learned the length of the year, that the four quarters of the year are not of equal length, and also observed the precession of the equinoxes. See armillary sphere. Before the time of the erection of a sun-dial in the Quirinus by L. Pap Doub′le-cyl′in-der pump. One having two cylinders in which the pistons act alternately. They may be single-acting or double-acting, that is, the cylinder may receive and deliver water at and from each end. The pumps of Hero of Alexandria, 150 B. C., were all single-acting, but one of them at least had a double cylinder. Dou′ble-cyl′in-der steam-en′gine. A form of engine having two communicating cylinders of varying capacities; there are many modifications in the arrangements and
1744 AD (search for this): chapter 4
ts aperture by the depression of the diaphragm upon the end of a pipe by means of a screw-plunger. Di′aphragmplate. A plate beneath the stage of a compound microscope, to restrict the amount of light reflected from the mirror. The plate has a number of holes of varying sizes, either of which may be brought to bear. Di′a-phragm-pump. A pump in which a diskpiston is attached by an elastic diaphragm, usually of leather, to the sides of the barrel. It was described by Desaguliers in 1744 as a piston without friction. It is much older than the time of this philosopher, however. It has been again and again re-invented, and brought out with a flourish of trumpets. See bag-pump. Its application may have been suggested by the human diaphragm. Di′as-tim′e-ter. A philosophical instrument for measuring distances. Di′a-style. （Architecture.) A system of columniation in which the width of the intercolumns is equal to three diameters of a column. Diatom-prism.
1741 AD (search for this): chapter 4
y means of a swing-frame. The circumference of the 45-inch circle was originally divided into five parts, each of these into three; these were then bisected four times, dividing the wheel into 240 parts, each of which was designed to contain nine teeth. Ramsden's screw-cutting apparatus. The first application of the tangent-screw and ratchet to the purpose of graduation is stated by Holtzapffel to have been by Pierre Fardoil. See plate 23 of Thiout's Traite d'horlogerie, etc., Paris, 1741. Fig. 1677 illustrates Ramsden's application of the principle of the engine just described in originating the screw of his dividingengine for straight lines. The guide-screw G is turned by the winch, and in each revolution moves the larger tangentwheel one tooth, winding on to the boss p a slip of watch-spring which carried the slide on which the tool t was fixed, thus cutting the screw C, which was at the same time rotated by the gearing c g from the prime shaft. The object was to cut a
1739 AD (search for this): chapter 4
an. Taken from a Brahminical idol by a French soldier; sold to the Empress Catherine for £ 90,000 and an annuity of £ 4,000. Weighs 194 carats. Pitt. Brought from India by Mr. Pitt, the grandfather of the first Earl of Chatham; sold to the Regent Duke of Orleans, in 1717, for £ 135,000. Weighed when rough, 400 carats; cut to 136 1/2 carats. Napoleon placed it in the hilt of his sword. Koh-i-noor. Seen by Tavernier in 1665, in the possession of the Great Mogul. Seized by Nadir Shah, in 1739, at the taking of Delhi. Became the property of Runjeet Sing. Captured by the English at the taking of the Punjab. Presented to the Queen by the East India Company, in 1850; weighed in the rough 800 carats, cut to 186 1/16 carats; recut to 103 3/4 carats. — Brande. Austrian. A rose-cut diamond of 139 1/2 carats. Sir Isaac Newton suggested that the diamond is combustible, but the first to establish the fact were the Florentine Academicians, in 1694; they succeeded in burning it in th
1740 AD (search for this): chapter 4
apped around the rod at right angles to the axis, the hypoteneuse gave the spiral of the screw, and the base the pitch. The subject of originating screws, which is closely connected with the dividing-engine, may be pursued in Holtzapffel (Vol. II. pp. 635 – 655). The methods of graduating instruments received much attention from Tompion (1660), Sharp (1689), the Sissons, and Bird (1745), the latter receiving pound 500 from the Board of Longitude for his method of dividing. Hindley, in 1740, constructed an engine for dividing circles, which also served to cut clock-wheels. Ramsden, in 1766, contrived his dividing-engine, and in 1777 received a reward of pound 615 from the Board of Longitude. Following Ramsden were the Troughtons, father and son, the latter of whom received the Copley medal of the Royal Society of England for his improved method of graduation. Ramsden's circular dividing-engine consisted of a large wheel moved by a tangent screw. The wheel was 45 inches i
1351 AD (search for this): chapter 4
the pendulum springs for chronometers. c is a draw-plate of metal for tube drawing. d are sections of wire of various shapes drawn through plates. e represents forms of pinion wire. f shows faney forms of wire used with others as pins in the surface of a wooden block used in calico-printing. The essential feature of wire-drawing is the drawplate. This was probably known at Nuremberg early in the fourteenth century, and how much before is not apparent. The History of Augsburg, 1351, and that of Nuremberg, 1360, mention the wire-drawer (Drahzieher). The draw-plate was imported into France by Archal, and into England by Schultz (1565). The drawplate is probably an Oriental invention. The draw-plate is made of a cylindrical piece of cast-steel, one side being flatted off. Several holes of graduated sizes are punched through the plate from the flat side, and the holes are somewhat conical in form. The wire is cleaned of its oxide in a tumbling-box, and is then annealed.
1511 AD (search for this): chapter 4
h patent of John Williams, 1692, is for an engine for carrying four men 15 fathoms or more under water in the sea, whereby they may work twelve hours together without any danger. It is stated to be useful in raising sunken vessels. It had a submerged chamber, communicating with the surface by a rigid tube, up and down which persons might pass. Projecting sleeves and hooks afforded means for directing grapnels to sunken property. Beckmann mentions a print in Vegetius on War, published in 1511 and 1532, representing a diver with his cap, from which rises a long leather pipe provided with an opening above the surface of the water. Lorini on Fortification, 1607, shows a square box, bound with iron, furnished with windows and a seat for the diver. Kessler in 1617, Witsen in 1671, and Borelli in 1679, gave attention to the subject and contributed to the efficiency of the apparatus. A diving-bell company was formed in England in 1688, and the operators made some sucessful descents
1514 AD (search for this): chapter 4
nce was ordered by Ptolemy Philadelphus in the college of Alexandria. He even authorized the vivisection of criminals condemned to death. Herophilus of Cos was among the first of the professors in this great school of medicine. The practice of dissection was very repugnant to the prejudices of the Egyptians, where to touch a corpse was defilement, as we see it also to have been among the Hebrews, who became habituated to many of the Egyptian modes of thought. Vesalius, born at Brussels 1514, died 1564, was among the most noted of the school of modern anatomists who have pursued the study of dissection. His distinguished professional career was terminated by an unfortunate affair, which turned out to be a vivisection, as the supposed cadaver proved to be living. The relatives who had granted the dissection denounced Vesalius to the Inquisition, who would have burned him but that Philip II. stepped in and had the sentence commuted to a pilgrimage to Jerusalem. Decidedly prefer
June, 1851 AD (search for this): chapter 4
es the whole body of the log to chip. The rotating drum has adjustable serrated cutters. The wood is fed on an inclined slide, and propelled by a toothed follower, actuated by a spur-wheel and rack. See also Barkplaning machine ; Rossing-machine. Dye-wood cutter. Dyke. 1. (Mining.) A bank of basalt or whin by which the strata or lodes are frequently divided. 2. A sea-wall. See dike. Dy-nacti-nom′e-ter. An instrument described by M. Claudet ( Philosophical magazine, June, 1851), for measuring the intensity of the photogenic rays of light, and computing the power of objectglasses. See actinometer. Dy-nam′e-ter. An instrument for measuring the magnifying power of a telescope. The magnifying power is the ratio of the solar focal distance of the object-glass to the focal distance of the eye-piece considered as a single lens; and this ratio being the same as the ratio of the diameter of the aperture of the telescope to the diameter of its image or disk for
1080 AD (search for this): chapter 4
ix times the length; six of these ribbons similarly treated and formed into one; six of the latter by a third operation, formed into one sliver; and five of these drawn into one, — will have the effect of placing the fibers parallel to each other 1080 times (6 × 6 × 6 × 5=1080). The drawing-frame for long-stapled wool is for drawing out and extending the slivers which have already been operated upon by the breaking-frame (which see). This is a repetitive operation, and it is usual to pass th1080). The drawing-frame for long-stapled wool is for drawing out and extending the slivers which have already been operated upon by the breaking-frame (which see). This is a repetitive operation, and it is usual to pass the wool through the breaking-frame and four times through the drawing-frame before roving. These slivers are united at each drawing, and are extended to, say, four times the length. The result is an actual extension and an oft-repeated laying of the slivers alongside of each other, so as to blend them and reduce inequalities. 2. (Silk-machinery.) A machine in which the fibers of floss or refuse silk are laid parallel, preparatory to being cut into lengths by the cutting-engine, to be afterw
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