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on 14th November 1879, in the throne-room of the Imperial palace, the archduchess solemnly abdicated all her rights of succession in Austria, in accordance with the law obliging all princesses of the Imperial house to do so when they wed a foreign prince. On 17th November the archduchess and her mother, with a numerous suite, started for Spain, arriving at the royal castle of El Pardo, near Madrid, on 24th November. The wedding took place in the Atocha cathedral, on 29th November, in great

underneath the fortress of Akershus. These works are intended to be the first in a general rearrangement of the entire harbour of the city. Population (1885), 128,301, counting in the suburbs; (1891), 151,239; (1898), 203,337, of whom 93,695 males, 109,642 females; (1900), 225,686. Christiansand, a fortified seaport town of Norway, on the S. coast. It is an important port of call for the Baltic steamboats, and a fishing centre. It was burnt down in 1892, and subsequently rebuilt of brick. It exports timber (nearly 3 million cubic feet annually), wood-state, and was followed by splendid festivities. Queen pulp, paper, fish, and felspar. The total trade is under half a million sterling. Christiansand owns about 100 vessels of 52,000 tons. An impetus was given to the trade and tourist traffic by the opening of the Sætersdal railway, tapping the interior, in 1895-96. Sawmills, wood-pulp factories, shipbuilding yards, and mechanical workshops are the principal industrial works. The cathedral was rebuilt after a fire in 1880. Population (1875), 11,766; (1900), 14,007.

Christianstad, a fortified town of Sweden, on a peninsula which juts out into Lake Sjövik, an expansion of the river Helge, 10 miles from the Baltic and 66 miles E. from Helsingborg by rail. It is the headquarters of several railway companies, and has flour mills, engineering works, distilleries, a weaving mill, sugar factory, &c., and exports granite and wood-pulp, and imports coal (40,000 to 70,000 tons), and wheat and rye. In 1896-97 its harbour at Ahus (pop. 1547) was enlarged and deepened to admit vessels drawing 18 ft., and a new entrance channel made. In 1899 it was entered by 530 vessels of 100,150 tons. A

new town hall was built in 1889. Population (1880),

9203; (1900), 10,318.

Christiansund, a seaport town of Norway, co. Romsdal, 83 miles W.S.W. from Trondhjem. It exports cod-fish, herrings, cod-liver oil, fish manure, &c., to the annual value of £350,000 to £550,000, and imports salt, coal, and colonial wares to about £55,000. Since 1894 butter has been exported to Great Britain. In 1892 an outlook tower was erected to commemorate the 150th anniversary of the founding of the town. Population (1875), 8251; (1898), 11,68

Christina bore her husband two daughters, before he died in 1885 Dona Mercedes, born 11th September 1880, and

Dona Maria Theresa, born 12th November 1882. During her husband's lifetime the young queen kept studiously apart from politics, so much so that her inexperience caused much anxiety in November 1885, when she was called upon to take the arduous duties of regent. During

the long minority of the posthumous son of Alfonso XII., the present King Alfonso XIII., the Austrian Queen-Regent acted in a way that obliged even the adversaries of the throne and the dynasty to respect the mother and the woman. The people of Spain, and the ever-restless civil and military politicians, found that the gloved hand of their constitutional ruler was that of a strong-minded and tenacious regent, who often asserted herself in a way that surprised them much, but always, somehow, commanded obedience and respect. More could not be expected by a foreign ruler from a nation little prone to waste attachment or demonstrative loyalty upon anybody not Castilian born and bred.

province of Vermland, Sweden, near the N.E. corner of Lake Wener, 25 miles by rail E. by S. from Carlstad. It has ironworks, a tobacco factory, &c., and large fairs are held every April and October. A part of the town was burnt down in 1893. Population (1880), 5039; (1900), 6775.

Christinehamn, or KRISTINEHAMN, a town of the

Scottish toxicologist and physician, was born in Edinburgh Christison, Sir Robert, Bart. (1797-1882), of that city in 1819, he spent a short time in London, on 18th July 1797. After graduating at the university studying under Abernethy and Lawrence, and in Paris, where he learnt analytical chemistry from Robiquet and heard lectures by Orfila, the famous toxicologist. In 1822 he returned to Edinburgh as professor of Medical Jurisprudence, and set to work to organize the study of his subject on a sound basis. On poisons in particular he speedily became a high authority; his well-known book on them was published in 1829, and in the course of his inquiries he did not hesitate to try such daring experiments on himself as taking large doses of Calabar bean. His attainments in medical jurisprudence and toxicology procured him the appointment, in 1829, of medical officer to the Crown in Scotland, and from that time till 1866 he was called as a witness in many celebrated criminal cases. In 1832 he gave up the chair of Medical Jurisprudence and accepted that of Medicine and Therapeutics, which he held till 1877; at the same time he became professor of Clinical Medicine, and continued in that capacity till 1855. His fame as a toxicologist and medical jurist, together with his work on the pathology of the kidneys and of fevers, secured him a large private practice, and he succeeded to a fair share of the honours that commonly attend the successful physician, being ceiving a baronetcy in 1871. Among the books which he published were a treatise on Granular Degeneration of the Kidneys (1839), and a Commentary on the Pharmacopoeias of Great Britain (1842). Sir Robert Christison, who retained remarkable physical vigour and activity

Christina, Maria Christina Henrietta Désirée Félicité Rénière, QUEEN-REGENT OF SPAIN (1858- -), widow of Alfonso XII. and mother of Alfonso XIII., was born at Gross Seelowitz, in Austria, on 21st July 1858, being the daughter of the Archduke Charles Ferdinand and the Archduchess Elizabeth of Austria. She was brought up by her mother as a rigid Catholic, and great care was taken with her education. At eighteen she was appointed, by the Emperor Francis Joseph, abbess of the House of Noble Ladies of Saint Theresa in Prague, where she made herself very popular and distinguished herself by her intellectual parts. It is said that at the Court of Vienna the archduchess saw the young Prince Alfonso of Spain when he was only a pretender in exile, before the restoration of the Bourbons. A few years later, when Alfonso XII. had lost his first wife and cousin, Queen Mercedes, daughter of the duc de Montpensier, his ministers, especially Señor Canovas, urged him to marry again. He told them that if he did so it would only be with the young Austrian Archduchess Maria Christina. After some negotiations between the two Courts and Governments, it was agreed that the Arch-appointed physician to Queen Victoria in 1848 and reduchess Elizabeth and her daughter should meet Alfonso XII. at Arcachon, in the south of France, where a few days' personal acquaintance was sufficient to make both come to a decision. The duke of Bailen went officially to Vienna to get the emperor of Austria's authorization, and

down to extreme old age, died at Edinburgh on 23rd | although the rocks of the southern coast of Java in their general January 1882.

Christmas Island, a British possession under the government of the Straits Settlements, situated in the eastern part of the Indian Ocean (in 10° 25' S. lat., 105° 42′ E. long.), about 190 miles S. of Java. It is not known when and by whom the island was discovered, but under the name of Moni it appears on a Dutch chart

of 1666. It was first visited in 1688 by Dampier, who found it uninhabited. In 1886 Captain Maclear of H.M.S. Flying Fish, having discovered an anchorage in a bay which he named Flying Fish Cove, landed a party and made a small but interesting collection of the flora and fauna. In the following year Captain Aldrich on H.M.S. Egeria visited it, accompanied by Mr J. J. Lister, F.R.S., who formed a larger biological and mineralogical collection. Among the rocks then obtained and submitted to Sir John Murray for examination there were detected specimens of nearly pure phosphate of lime, a discovery which eventually led, in June 1888, to the annexation of the island to the British Crown. Soon afterwards a small settlement was established in Flying Fish Cove by Mr G. Clunies Ross, the owner of the Keeling Islands, which lie about 750 miles to the westward. In 1891 Mr Ross and Sir John Murray were granted a lease, but on the further discovery of phosphatic deposits they disposed of their rights in 1897 to the company now in possession. In the same year a thorough scientific exploration was made, at the cost of Sir John Murray, by Mr C. W. Andrews, of the British Museum.

Physical Features and Geology.-The island is a quadrilateral with hollowed sides, about 12 miles in greatest length and 9 in extreme breadth. It is about 190 miles from the nearest land, and is probably the only tropical island that had never been inhabited by man. When the first settlers arrived, in 1897, it was covered with a dense forest of great trees and luxuriant undershrubbery. The settlement in Flying Fish Cove now numbers some 250 inhabitants, consisting of Europeans, Sikhs, Malays, and Chinese, by whom roads are being cut and patches of cleared ground cultivated. The island is the flat summit of a submarine mountain more than 15,000 feet high, the depth of the platform from which it rises being about 14,000 feet, and its height above the sea being upwards of 1000 feet. The submarine slopes are steep, and within 20 miles of the shore the depth of the sea reaches 2400 fathoms. It consists of a central plateau descending to the water in three terraces, each with its "tread" and "rise. The shore terrace descends by a steep cliff to the sea, forming the "rise" of a submarine "tread" in the form of fringing reef which surrounds the island and is never uncovered, even at low water, except in Flying Fish Cove, where the only landing-place exists. The central plateau is a plain whose surface presents "rounded, flat-topped hills and low ridges and reefs of limestone," with narrow intervening valleys. On its northern aspect this plateau has a raised rim having all the appearances of being once the margin of an atoll. On these rounded hills occurs the deposit of phosphate of lime which gives the island its commercial value. The phosphatic deposit has doubtless been produced by the longcontinued action of a thick bed of sea-fowl dung, which converted the carbonate of the underlying limestone into phosphate. The flat summit is formed by a succession of limestones-all deposited in shallow water-from the Eocene (or Oligocene) up to recent deposits in the above-mentioned atoll with islands on its reef. The geological sequence of events appears to have been the following:-After the deposition of the Eocene (or Oligocene) limestone-which reposes upon a floor of basalts and trachytesbasalts and basic tuffs were ejected, over which, during a period of very slow depression, orbitoidal limestones of Miocene agewhich seem to make up the great mass of the island-were deposited; then elapsed a long period of rest, during which the atoll condition existed and the guano deposit was formed; from then down to the present time there has succeeded a series of sea-level subsidences, resulting in the formation of the terraces and the accumulation of the detritus now seen on the first inland cliff, the old submarine slope of the island. The occurrence of such a series of Tertiary deposits appears to be unknown elsewhere. The whole series was evidently deposited in shallow water on the summit of a submarine volcano standing in its present isolation, and round which the ocean floor has probably altered but a few hundred feet since the Eocene age. Thus

characters and succession resemble those of Christmas Island, there lies between them an abysmal trough 18,000 feet in depth, which renders it scarcely possible that they were deposited in a continuous area, for such an enormous depression of the sea-floor could hardly have occurred since Miocene times without involving also Christmas Island. One of the main purposes of the exploration was to obtain light on the question of the foundation of atolls. As a result of the investigation it has been found that "the great thickness of reef limestone required by the Darwinian theory of atoll formation" does not exist, and although there may be some evidence that subsidence did occur in the earlier history of the island, it is clear that it was neither continuous for any long period nor of any great extent" (Andrews). If Christmas Island cannot, perhaps, be proved to have been a typical atoll, it can, however, "be shown that at one time it must have consisted of reefs and islands approximating very nearly to those seen on atolls which are regarded as typical, and the determination of the nature of the foundation upon which those reefs and islands rested is, at least, a step in the right direction (Andrews).

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Flora and Fauna.-The flora consists of 129 species of angiosperms, 1 Cycas, 22 ferns, and a few mosses, lichens, and fungi, 17 of which are endemic, while a considerable number- not specifically distinct-form local varieties nearly all presenting Indo-Malayan affinities, as do the single Cycas, the ferns, and the cryptogams. As to its fauna, the island contains 319 species of animals-54 only being vertebrates-145 of which are endemic. A very remarkable distributional fact in regard to them, and one not yet fully explained, is that a large number show affinity with species in the Austro-Malayan rather than in the Indo-Malayan, their nearer, region. The ocean currents, the trade-winds blowing from the Australian mainland, and north-westerly storms from the Malayan islands, are no doubt responsible for the introduction of many, but not all, of these Malayan and Australasian species.

Climate. The climate is healthy, the temperature varying from 75° to 84° F. The prevailing wind is the S. E. trade, which blows the greater part of the year. The rainfall in the wet season is heavy, but not excessive, and during the dry season the ground is refreshed with occasional showers and heavy dews. Malarial fever is not prevalent, and it is interesting to note that there are no swamps or standing waters on the island.

See ANDREWS, C. W. A Monograph of Christmas Island (Indian Ocean), London, 1900, to which the present writer has been greatly indebted. (H. O. F.)

Chronographs. In the article GUNNERY (Ency. Brit. vol. xi.) descriptions were given of some chronographs adapted for the determination of the velocities of projectiles. Some additional forms of instruments both for this

and for other purposes are here described.

Gun Chronographs.-Probably the earliest forms of chronographs, not based on the ballistic pendulum method, are due to Colonel Grobert, 1804, and Colonel Dabooz, 1818, both officers of the French

army.

In the instrument by Grobert two large discs, attached to the same axle 13 ft. apart, were rapidly rotated; the shot pierced each disc, the angle between two holes giving the time of flight of the ball, when the angular velocity of the discs was known. In the instrument by Colonel Dabooz a cord passing over two light pulleys, one close to the gun, the other at a given distance from it, was stretched by a weight at the gun end and by a heavy screen at the other end. Behind this screen there was a fixed screen. The shot cut the cord and liberated the screen, which was perforated during its fall. The height of fall was measured by superposing the hole in the moving screen upon that in the fixed one. This gave the approximate time of flight of the shot over a given distance, and hence its velocity.

In the early form of chronoscope invented by Wheatstone in 1840 the period of time was measured by means of a species of clock, driven by a weight; the dial pointer was started and stopped by the action of an electromagnet which moved a pawl engaging with a toothed wheel fixed on the axle to which the dial pointer was attached. The instrument applied to the determination of the velocity of shot is described thus by Wheatstone :

"A wooden ring embraced the mouth of the gun, and a wire connected the opposite sides of the ring. At a proper distance the target was erected, and so arranged that the least motion given to it would establish a permanent contact between two metal points. One of the extremities of the wire of the electromagnet (before mentioned) was attached to one pole of a small battery; to the other extremity of the electromagnet were attached two wires, one of which communicated with the contact piece of the target, and the other with one of the ends of the wire stretched across the mouth of the gun; from the other extremity of the voltaic battery

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two wires were taken, one of which came to the contact piece of the target, and the other to the opposite extremity of the wire across the mouth of the gun. Before the firing of the gun a continuous circuit existed, including the gun wire; when the target was struck the second circuit was completed; but during the passage of the projectile both circuits were interrupted, and the duration of this interruption was indicated by the chronoscope." Professor Henry (Journal Franklin Inst., 1886) employed a cylinder driven by clockwork, making ten revolutions per second. The surface was divided into 100 equal parts, each equal to Tobo second. The time marks were made by two galvanometer needles, when successive screens were broken by a shot. Henry also used an induction-coil spark to mark the cylinder, the primary of the coil being in circuit with a battery and screen. This form of chronograph is in many respects similar to the instrument of Konstantinoff, which was constructed by Breguet and has been sometimes attributed to him (Les Comptes Rendus, 1845). This chronograph consisted of a cylinder 1 m. in circumference and 0.36 m. long, driven by clockwork, the rotation being regulated by a governor provided with wings. A small carriage geared to the wheelwork traversed its length, carrying electromagnetic signals. The electric chronograph signal usually consists of a small armature (furnished with a style which marks a moving surface) moving in front of an electromagnet, the armature being suddenly pulled off the poles of the electromagnet by a spring when the circuit is broken (Journal of Physiology, vol. ix. p. 408). The signals in Breguet's instrument were in a circuit, including the screens and batteries of a gun range. The measurement of time depended on the regularity of rotation of the cylinder, on which each mm. represented bo second.

In the Navez chronograph (1848) the time period is found by means of a pendulum held at a large angle from the vertical by an electromagnet, which is in circuit with a screen on the gun range. When the shot cuts this screen, the circuit is broken and the pendulum liberated and set swinging. When the next screen on the range is broken by the shot, the position of the pendulum is recorded and the distance it has passed through measured on a divided arc. From this the time of traversing the space between the screens is deduced. By means of an instrument known as a disjunctor (Ency. Brit. vol. xi. p. 300) the instrumental time-loss or latency of the chronograph is determined. In Benton's chronograph (1859) two pendulums are liberated, in the same manner as in the instrument of Navez, one on the cutting of the first screen, the other on the cutting of the second. The difference between the swings of the two pendulums gives the time period sought for. The disjunctor is also used in connexion with this instrument. In Vignotti's chronograph (1857) again a pendulum is employed, furnished with a metal point, which moves close to paper impregnated with ferro-cyanide of potassium. The gun-range screens are included in the primary circuits of induction coils; when these circuits are broken a spark from the pointer marks the paper. From these marks the time of traverse of the shot between the screens is determined.

Colonel Sebert (Extraits du Mémorial de l'Artillerie de la Marine) devised a chronograph to indicate graphically the motion of recoil of a cannon when fired. A pillar fixed to the ground at the side of the gun-carriage supported a tuning-fork, the vibration of which was maintained electrically. The fork was provided with a tracing point attached to one of the prongs, and so adjusted that it drew its path on a polished sheet of smoke-blackened metal attached to the gun-carriage, which traversed past the tracing point, when the gun ran back. The fork used made 500 complete vibrations per second. A central line was drawn through the curved path of the tracing point, and every entire vibration cut the straight line twice, the interval between each intersection equalling To second. The diagram so produced gave the total time of the accelerated motion of recoil of the gun, the maximum velocity of recoil, and the rate of acceleration of recoil from the beginning to the end of the motion. By means of an instrument furnished with a microscope and micrometers, the length and amplitude, and the angle at which the curved line cut the central line, were measured. At each intersection (according to the inventor) the velocity could be deduced. The motion at any intersection being compounded of the greatest velocity of the fork, while passing through the midpoint of the vibration and the velocity of recoil, the tangent made by the curve with the straight line represents the ratio of the velocity of the fork to the velocity of recoil. If a be the amplitude of vibration, considered constant, the velocity of the fork at the midpoint of its path, r the velocity of recoil, a the angle made by the tangent to the curve with the straight line at the point of intersection, and t the line of a complete vibration; then,

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drum, divided on its edge so that when a vernier is used a minute. of angle may be read, is rotated rapidly by a motor at a practically uniform speed. The points of a row of steel-pointed pins, screwed into a frame of ebonite, can be brought within inch of the surface of the drum. Each pin is a part of the secondary circuit of an induction coil, the space between the pins and the drum forming spark gaps. The drum is rubbed over with a weak solution of paraffin wax in benzol, which causes the markings produced by the sparks to be well defined. The records are read by means of a fine hair stretched along the drum and just clear of it, the dots being located under the hair by means of a lens. The velocity of rotation is found by obtaining spark marks, due to the primary circuits of two induction coils being successively broken by a weight falling and knocking over two light levers. The distance between the levers is about 3.77 inch, and the time of fall between the levers is 0.018948 sec. In practice two drop weights are used, to avoid the chance of an experiment being wasted. This chronograph has been used for finding the velocity of projectiles after leaving the gun, and also for finding the rate at which a shot traverses the bore. For the latter purpose the shot successively cuts insulated wires fixed in plugs screwed into the gun at known intervals; each wire forms a part of the primary of an induction coil, and as each is cut a dot is made on the rotating drum by the induced spark.

Jervis-Smith's tram chronograph was devised for measuring periods of time varying from about one-fourth to one twenty-thousand th part of a second (Proc. Roy. Soc. vol. xlv. p. 452. Improved from Pat. 1894. The Tram Chronograph, by F. J. Jervis-Smith, F.R.S.). It consists of a metal girder having a T-shaped end. This carries two parallel steel rails, the edges of which lie in the same vertical plane. The girder is supported at its end, and at the extremities of the T-piece, on the V-groove, trihedral hole, and plane system. A carriage or tram furnished with three grooved wheels runs on the rails, and a slightly-smoked glass plate is attached to its vertical side. The tram in the original instrument was propelled by a falling weight, but in an improved form one or more spiral springs are employed. All time traces are made immediately after the propelling force has ceased to act. The tram is brought to rest by a gradually applied brake, consisting of two crossed leather bands stretched by two springs; a projection from the tram runs between the bands, and brings it to rest with but little lateral pressure.. When, for certain physiological experiments, a low velocity of traverse is required, a heavy flywheel is mounted on the tram and geared to its wheels. A pillar also mounted on the hole, groove and plane method, is placed vertically in front of the glass, to carry the electromagnetic signals, which can be brought into contact with the glass by means of a tangent-screw. A standard fork by Koenig fixed to a pillar also makes a trace on the glass, being automatically thrown into vibration. Tuning - forks may be calibrated by obtaining two signal markings on the plate, controlled by a standard clock of known rate. Two motions of a slide on the pillar, viz., of rotation and translation, allow a number of observations to be made. The traces are counted out on a sloping glass desk, and the time of flight of a projectile between two or more screens is found. When very close readings are required, they are made by means of a traversing micrometer microscope. If the instrument is used for gun work, the tram is driven at full speed; when the distance between the screens is known, and also the time of flight, the midpoint velocity is found by applying Bashforth's formula. When the velocity of shot from a shot-gun has to be found, a thin wire stretched across the muzzle takes the place of the first screen, and a thin sheet of metal or cardboard carrying an electric contact, or a Branly coherer, takes the place of the second screen. The electric firing circuit is provided with a safety key attached by a cord to the man who loads the gun and prepares the electric fuse, thus preventing him from getting into the line of fire when the gun is fired by the chronograph. (Pat. Record, 1897.) The tram, when the instrument is adjusted, has a practically constant velocity of traverse.

The polarizing photo-chronograph, designed and used by Dr A. Cushing Crehore and Dr G. Owen Squier at the United States Artillery School (Journal United States Artillery, 1895, vol. vi. p. 271), depends for its indications upon the rotation of a beam of light by a magnetic field, produced by a solenoidal current, which is opened and closed by the passage of the projectile. The general arrangement is as follows:-A beam of light from an electric lamp traverses a lens, then a Nicol prism, next a glass cylinder furnished with plane glass ends and coiled with insulated wire, then an analyser and two lenses, finally impinging on a photographic plate to which rotation is given by an electric motor, the plane of rotation being perpendicular to the direction of the beam of light. The same plate also records the shadow of a pierced projection attached to a tuning-fork, light from the electric lamp being diverted by a mirror for this purpose. The solenoid used to produce a magnetic field across the glass cylinder, which is filled with carbon bisulphide, is in circuit with a dynamo, resistances, and

the screens on the gun range. It is a well-known phenomenon in physics that when, with the above-mentioned combination of polarizing Nicol prism and analyser, the light is shut off by rotating the analyser, it is instantly restored when the carbon bisulphide is placed in a magnetic field. This phenomenon is utilized in this instrument. The projectile, by cutting the wire screens, causes the magnetic field to cease and light to pass. By means of an automatic switch the projectile, after cutting a screen, restores the electric circuit, so that successive records are registered. After a record has been made it is read by means of a micrometer microscope, the angle moved through by the photographic disc is found, and hence the time period between two events. In the photo-chronograph described in Untersuchungen über die Vibration des Gewehrlaufs, by C. Cranz and K. R. Koch, München, 1899, also note on the same, Nature, vol. lxi. p. 58, a sensitive plate moving in a straight line receives the record of the movement of the barrels of firearms when discharged. It was mainly used to determine the "angle of error of departure" in ballistics.

Astronomical Chronographs.-The astronomical chronograph is an instrument whereby an observer is enabled to register the time of transit of a star on a sheet of paper attached to a revolving cylinder. A metal cylinder covered with a sheet of paper is rotated by clockwork controlled by a conical pendulum, or by a centrifugal clock governor such as is used for driving a telescope. By means of a screw longer than the cylinder, mounted parallel with the axis of the cylinder and rotated by the clockwork, a carriage is made to traverse close to the paper. In some instruments this carriage is furnished with a metal point, and in others with a stylographic ink pen. The point or pen is made to touch the paper by an electromagnet the electric current of which is closed by the observer at the transit instrument, and a mark is recorded on the revolving cylinder. The movement of the same point or pen is also controlled by a standard clock, so that at the end of each second a mark is made. The cylinder makes one revolution per minute, and the minute is indicated by the omission of the mark. In Dent's form (Nature, vol. xxiii. p. 59) continuous observations can be recorded for 6 hours. The conical pendulum used to govern the rotation of the cylinder was the invention of Sir G. B. Airy. The lower end is geared to a metal plate which sweeps through an annular trough filled with glycerine and water. When the path of the pendulum exceeds a certain diameter it causes the plate to enter the liquid more deeply, its motion being thereby checked; also, when the pendulum moves in a smaller circle, the plate is lifted out of the liquid and the resistance is diminished in the same proportion as the force. The compensatory action is considerable; doubling the driving power produces no perceptible difference in the time. To prevent the injury of the conical pendulum and the wheel work by any sudden check of the cylinder, a ratch-wheel connexion is placed between the cylinder and the train of wheel work; this enables the pendulum to run on until it gradually comes to rest. dulum, which weighs about 18 lb, is compensated, and makes one revolution in two seconds; it is suspended from a bracket by means of two flexible steel springs placed at right angles to one another.

The pen

In the astronomical chronograph designed by Sir Howard Grubb, F.R.S. (Proc. Inst. Mech. Eng., July 1888), the recording cylinders -two in number-are driven by a weight acting on a train of wheel work controlled by an astronomical telescope governor. The peculiar feature of this instrument is that the axle is geared to a shaft which communicates motion to the cylinders through a mechanism whereby the speed of rotation is constantly corrected by a standard clock. Should the rotation fall below the correct speed, it is automatically accelerated, and if its speed of rotation rises above the correct one, it is retarded. The accelerator and retarder are thrown into action by electromagnets, controlled by a "detector" mounted on the same shaft. The rather complicated mechanism employed to effect the correction is described and fully illustrated in the reference given. The cylinders are covered with paper, but all the markings are made with a stylographic pen. The marks indicating seconds are dots, but those made by the observer are short lines. When an observation is about to be made, the observer first notes the hour and minute, and, by pressing a contact key attached to a flexible cord at the transit instrument, marks the paper with a letter in Morse telegraph characters, indicating the hour and minute; he then waits till a micrometer wire cuts a star and at the instant closes the circuit, so that the second and fraction of a second are registered on the chronograph paper. When a set of observations have been taken, the paper is removed from the cylinder, and the time results are obtained by applying a suitably divided rule to the marked paper, fractions of a second being estimated by applying a piece of glass ruled with eleven straight lines converging to a point. The ends of these lines on the base of the triangle so formed are equidistant on one edge of the glass, so that when the first and last lines are so placed as to coincide with the beginning and end of the markings of a second,

that second is divided into ten equal parts. The base of the
triangle is always kept parallel with the line of dots.
The papers,
after they have been examined and the results registered, are kept
for reference.
The observatory of Washburn, University of Wisconsin, is
furnished with a chronograph of the same type as that of Dent
(Annals Harvard Coll. Obs. vol. i. pt. ii. p. 34), but in this
instrument the rotation of the cylinder is controlled by a double
conical pendulum governor of peculiar construction.
When the
balls fly out beyond a certain point, one of them engages with a
hook attached to a brass cylinder which embraces the vertical axle
loosely. When this mass is pulled aside the work done on it
diminishes the speed of the governor. The pendulum ball usually
strikes the hook from 60 to 70 times per minute. Governors on
this principle were adopted by Alvan Clark for driving heliostats
in the United States Transit of Venus Expedition, 1874.

Acoustic Chronographs.-A chronograph was devised by Regnault (Acad. des Sc., 1868) to determine the velocity of sound propagated through a great length of pipe. A band of paper 27 mm. wide was continuously unrolled from a bobbin by means of an electromagnetic engine. In its passage over a pulley it passed over a smoky lamp flame, which covered it with a thin deposit of carbon. It next passed over a cylinder in contact with the style of a tuning-fork kept in vibration by electromagnets placed on either side of its prongs, the current being interrupted by the fork; it was also in contact with an electric signal controlled by a standard clock. Also an electromagnetic signal marked the beginning and end of a time period. Thus three markings were registered on the band, viz., the time of the pendulum, the vibrations of the fork, and the marking of the signal due to the opening and closing of the current by electrical contacts attached to diaphragms on which the sound wave acted. The contacts consisted of minute hammers resting on metal points fixed to the centre of diaphragms which closed the end of the experimental pipes. The signal marked the instant at which a sound wave impinged on a diaphragm. The markings on the paper band gave the period of time between two events, and the number of vibrations of the tuning-fork per second were estimated by means of markings due to the clock. The sound wave was usually originated by firing a pistol into the pipe furnished with diaphragms and contact pieces.

In the chronographic use of the Morse telegraph instrument (Stewart and Gee, Elementary Practical Phys. p. 234) a circuit is arranged which includes a seconds pendulum furnished with a fine platinum wire below the bob, which sweeps through a small mass of mercury forming a part of the circuit. There is a Morse key for closing the circuit. A fast-running Morse instrument and a battery are placed across this circuit as a shunt. A succession of dots is made on the paper ribbon by the circuit being closed by the pendulum, and the space between each adjacent dot indicates a period of one second's duration. Also, when the key is depressed, a mark is made on the paper. To measure a period of time, the key is depressed at the beginning and end of the period, causing two dots to be made on the ribbon; the interval between these, when measured by the intervals due to the pendulum, gives the length of the period in seconds, and also in fractions of a second, when the seconds' interval is subdivided into convenient equal parts. This apparatus has been used in determination of the velocity of sound. In the break circuit arrangement of pendulum key and Morse instrument the markings appear as breaks in a line which would otherwise be continuous. This combination was employed by Professors Ayrton and Perry in their determination of the acceleration of gravity at Tokio, 1877-78 (Proc. Phys. Soc. London, vol. iii. p. 268).

In the tuning-fork electro-chronograph attributed to Hipp a metal cylinder covered with smoked glazed paper is rotated uniformly by clockwork, a tuning-fork armed with a metallic style being so adjusted that it makes a clear fine line on the smoked paper. The tuning-fork is placed in the secondary circuit of an induction coil, so that when the primary circuit is broken an induced spark removes a speck of black from the paper and leaves a mark. The time period is deduced by counting the number of vibrations and fractions of vibration of the tuning-fork as recorded by a sinuous line on the cylinder. In later forms of this instrument the cylinder advances as it rotates, and a spiral line is traced. To obtain good results the spark must be very small, for when large it often leaps laterally from the end of the style, and does not give the true position of the style when the circuit is broken. The same arrangement of tuning-fork and revolving cylinder, with the addition of a standard clock, has been used by Mayer (Trans. National Academy of Sciences U.S.A. vol. iii.) and others for calibrating tuning-forks, and comparing their vibrations directly with the beats of the pendulum of a standard clock the rate of which is known. The pendulum makes and breaks the primary circuit by carrying a small platinum wire through a small mercury meniscus. Better and apparently certain contacts can be obtained from platinum contact-pieces, S. III. - 9

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brought together above the pendulum by means of a toothed wheel on the scape-wheel arbor. Sparking at the contact points is greatly reduced by placing a couple of lead plates in dilute sulphuric acid as a shunt across the battery circuit.

For physiological purposes.-Fick's pendulum myograph or muscletrace recorder is described in Vierteljahrschr. der Naturforsch. Ges. in Zürich, 1862, s. 307, and in Text-book of Physiology, M. Foster, pp. 42, 45. It was used to obtain a record of the contraction of a muscle when stimulated. In many respects the instrument is similar to the electro-ballistic chronograph of Navez. A long pendulum, consisting of a braced metal frame, carries at its lower end a sheet of smoked glass. The pendulum swings about an axis supported by a wall bracket. Previous to an experiment, the pendulum is held on one side of its lowest position by a spring catch; when this is depressed it is free to swing. At the end of its swing it engages with another spring catch. In front of the moving glass plate a tuning-fork is fixed, also a lever actuated by the muscle to be electrically stimulated. When the pendulum swings through its arc, it knocks over the contact key in the primary circuit of an induction coil, the secondary of which is in connexion with the muscle. The smoked plate receives the traces of the style of the tuning-fork and of the lever attached to the muscle, and also the trace of an electromagnetic signal which marks the instant at which the primary circuit is broken. After the traces are made, they are ruled through with radial lines, cutting the three traces, and the time intervals between different parts of the muscle curve are measured in terms of the period of vibration of the tuning-fork, as in other chronographs in which the tuning-fork is employed.

In the spring myograph of Du Bois Reymond (Munk's Physiologie der Menschen, p. 398) a smoked glass plate attached to a metal rod is shot by a spiral spring along two guides with a velocity which is not uniform. The traces of a style moved by the muscle under examination, and of a tuning-fork, are recorded on the glass plate, the shooter during its traverse knocking over one or more electric keys, which break the primary circuit of an induction coil, the induced current stimulating the muscle.

In the photo-electric chronograph devised by Mr G. J. Burch (Journal of Physiology, vol. xviii. p. 125; Electrician, vol. xxxvii. p. 436) the rapid movements of the column of mercury in a capillary electrometer used in physiological research are recorded on a sensitive plate moving at a uniform angular velocity. The trace of the vibrating prongs of a tuning-fork of known period is also recorded on the plate, the light used being that of the electric arc. The images of the meniscus of the mercury column and of the moving fork are focussed on the plate by a lens. Excellent results have been obtained with this instrument.

The

An important development of a branch of chronography is due to Marey (Comptes Rendus, 7 Août 1882, and Le Mouvement, par E. S. Marey, Paris, 1894), who employed a photographic plate for receiving successive pictures of moving objects, at definite times, when investigating the movements of animals, birds, fishes, insects, and also microscopic objects such as vorticella. instrument in one of its forms consisted of a camera and lens. In front of the sensitive plate and close to it a disc, pierced with radial slits, revolved at a given angular velocity, and each time a slit passed by the plate was exposed. But since, in the time of passage of the space between the slits, the object had moved by a certain amount across the field of view, a fresh impression was produced at each exposure. The object, well illuminated by sunlight, moved in front of a black background. Since the angular velocity of the disc was known, and the number of slits, the time between the successive positions of the object was also known.

Marey (La Méthode graphique, pp. 133, 142, 456), by means of pneumatic signals and a rotating cylinder covered with smoked glazed paper, measured the time of the movements of the limbs of animals. The instrument consists of a recording cylinder rotated at a uniform angular velocity by clockwork controlled by a fan governor, and pneumatic signal, constructed thus. One end of a closed shallow cylinder, about 4 cm. dia., is furnished with a stretched rubber membrane. A light lever, moving about an axis near the edge of the cylinder, is attached to the centre of the membrane by a short rod, its free end moving as the membrane is distended. The cylinder is connected by a flexible tube with a similar cylinder and membrane, but without a lever, which is attached to that part of the body of the animal the movement of which is under investigation. The system is full of air, so that when the membrane attached to the animal is compressed, the membrane which moves the lever is distended and the lever moved. Its end, which carries a scribing point, marks the smoked paper on the rotating cylinder. The pneumatic signal is called by Marey "tambour à levier."

REFERENCES TO CHRONOGRAPHIC METHODS-(i.) Chronographs used in Physiology:-HELMHOLTZ. Verhandlungen der physikalischmedicinischen Gesellschaft in Wurtzburg. N. F. 1872, Bd. II. S. 147.-HARLESs. "Das Atwood'sche Myographion," Abhandlungen der k. Bayerischen Akademie der Wissenschaften. II. Cl. Bd. IX.

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Abth. 11, München, 1862, S. 361.-Fall-Myographion aufgestellt in der Wiener Weltausstellung in der Abtheilung für das Unterrichtswesen von Ungarn, Budapest, 1873.-HENSEN. "Myographion mit vibratorischer Bewegung," Arbeiten aus dem Kieler physiol. Instit. 1868, S. 108.-BRÜCKE. Sitzungsber. d. Wiener Acad. LXXV. 3. Abth., Sep. Abdr. 1877.-PFLUEGER. "Myographion ohne Bewegung," Untersuchungen über die Physiologie des Electrotonas. S. 106, Berlin, 1859.-POUILLET. Compt. Rend. xix. p. 1384. 1844.-LUDWIG. "Kynographion."-PFLUEGER. "Cylinder governed by conical pendulum," Phys. der Menschen, Munk.-YOUNG, THOS. "Early form of cylinder chronograph,' Life in Motion, M'Kendrick, p. 55. (ii.) Chronographs used in gun work and for other purposes:-SABINE. Phil. Mag. 1876. -SCHULTZ. Moisson, ed. Tanera. Paris.-PAUL LA COUR. La Roue Phonique. Copenhagen, 1878.-MACH. Collected papers on chronographs, Nature, vol. xlvii. p. 250.-Boys. "Bullets photographed in flight," B. A. meeting, Edinburgh, 1892; reported in Nature, vol. xlvii. p. 415.-PNEUMATIC TUBE Co., Paris. Chronograph," Nature, vol. viii. p. 106. - FOSTER. Nature, vol. xiii. p. 139.-HOLDEN. Nature, vol. xxvi. p. 368.– D'ARSONVAL. La Lumière Electrique. 1887.-DUNn. "The Photo-Retardograph," Journal U.S. Artillery, vol. vii. p. 29.DEPREZ. Accélérographe," La Méthode graphique, Marey, p. 174. Paris, 1878.-SIEMENS (Werner). Electric spark chronograph,' Annalen der Phys., Poggendorff, 66. 1845. (F. J. J.-S.)

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Chronological Table.—The following table of the leading events in every country in the world has been prepared in continuation of the table published in the ninth edition of this work, which brought down the record to the close of 1875. It must always be difficult to determine what events should or should not appear in such a chronicle, but in this brief abstract the aim has been to include rather than to exclude, with a view to making the table a really useful aide-mémoire :—

1876. Chapter of Knights of the Star of India held by the Prince of Wales in Calcutta, January 1. Death of Francis Deák, January 28. Administrative reform Note presented to Turkey by the Great Powers, January 31. Perak River insurgents defeated by the British, February 4. Prince Bismarck's reply to the charge of warlike designs, February 10. Purchase of Suez Canal shares voted by the House of Commons, February 21. Don Carlos retires from Spain, February 27. Incorporation of Khokand in the Russian Empire, March 13. Royal Titles Bill passed by the House of Commons, March 23. Philadelphia Centennial Exhibition opened, May 10. British fleet arrives in Besika Bay, May 26. Turkish massacres in Bulgaria, May. Deposition of Sultan Abdul Aziz, May 30. First railway opened in China, June 3. Death of Lord Sandhurst, June 23 (born, 1819). Slaughter of United States troops by Sioux Indians, June 25. Death of Miss Harriet Martineau, June 27 (born, 1802). Servia and Montenegro declare war against Turkey, July 2. Mr Disraeli created Earl of Beaconsfield, August 16. Deposition of Sultan Murad V., August 31. Sir T. Wade's treaty with China ratified, September 17. General Tchernaieff proclaims Prince Milan King of Servia, September 20. Mr Goschen's financial mission to Egypt, October 14. Spanish army under General Martinez Campos sent to Cuba to suppress the insurrection, October 15. Capture of Alexinatz by the Turks Russian demand for an armistice between Turkey and Servia, October 31. Speech by Lord Beaconsfield on the Turkish question, November 9. Porfirio Diaz, having defeated the Government troops, becomes Provisional President of Mexico, November 20. Death of the Duke of Saldanha, November 21 (born about 1790). Mr Hayes elected President of the United States, December 6. Meeting in Constantinople of the Plenary Conference on Turkish affairs, December 24.

1877. Queen Victoria proclaimed Empress of India at Delhi, January 1. Turkish issue of £7,000,000 paper money, January 5. National Defence Society formed in Athens, January 7. German general election: majority for National Liberal party, January 10. Continued famine in India announced, January 12. The Porte declines the administrative reform proposals of the Powers, January 20. Anti-clerical Bill passed by the Italian Chamber of Deputies,. January 24. Banishment of Midhat Pasha, Grand Vizier of Turkey, February 5. Death of Sir W. Fergusson, February 10 (born, 1808). Col. Gordon appointed Governor of the Sudan, February 12. Death of Gen. Changarnier, February 14 (born, 1793). Gen. Porfirio Diaz elected President of Mexico, February 18. Defeat of Japanese rebels near Kagosima, February 23. Death of Sir Jung Bahadur of Nepal, February 25. Peace treaty between Turkey and Servia, March 1. Papal allocution on restriction of liberty, March 12. Protocol signed by the Great Powers regarding the Eastern question, March 31. Arrival of Sir Bartle Frere at Cape Town as High Commissioner, March 31. Annexation of

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