Chapter XII: Front Matter (12)

The four Aristotelian causes are: (1) _Material cause_ ([Greek: yle]) the material out of which a thing is made; the material cause of a house is the bricks and mortar of which it is composed. (2) _Formal cause_ ([Greek: eidos, logos, to ti en einai]), the general external appearance, shape, form of a thing; the formal cause of a triangle is its triangularity. (3) _Efficient cause_ ([Greek: arche tes kineseos]), the alcohol which makes a man drunk, the pistol-bullet which kills. This is the cause as generally understood in modern usage. (4) _Final cause_ ([Greek: telos, to ou eneka]), the object for which an action is done or a thing produced; the final cause of a commercial man's enterprise is to make his livelihood (see TELEOLOGY). This last cause was rejected by Bacon, Descartes and Spinoza, and indeed in ordinary usage the cause of an action in relation to its effect is the desire for, and expectation of, that effect on the part of the agent, not the effect itself. The _Proximate cause_ of a phenomenon is the immediate or superficial as opposed to the _Remote_ or _Primary cause_. Plurality of Causes is the much criticized doctrine of J.S. Mill that a fact may be the uniform consequent of several different antecedents. _Causa essendi_ means the cause whereby a change is what it is, as opposed to the _causa cognoscendi_, the cause of our knowledge of the event; the two causes evidently need not be the same. An object is called _causa immanens_ when it produces its changes by its own activity; a _causa transiens_ produces changes in some other object. _Causa sui_ is a term applied to God by Spinoza to denote that he is dependent on nothing and has no need of any external thing for his existence. _Vera causa_ is a term used by Newton in his _Principia_, where he says, "No more causes of natural things are to be admitted than such as are both true and sufficient to explain the phenomena of those things"; _verae causae_ must be such as we have good inductive grounds to believe do exist in nature, and do perform a part in phenomena analogous to those we would render an account of.

CAUSEWAY, a path on a raised dam or mound across marshes or low-lying ground; the word is also used of old paved highways, such as the Roman military roads. "Causey" is still used dialectically in England for a paved or cobbled footpath. The word is properly "causey-way," from _causey_, a mound or dam, which is derived, through the Norman-French _caucie_ (cf. modern _chaussee_), from the late Latin _via calciata_, a road stamped firm with the feet (_calcare_, to tread).

CAUSSES (from Lat. _calx_ through local Fr. _caous_, meaning "lime"), the name given to the table-lands lying to the south of the central plateau of France and sloping westward from the Cevennes. They form parts of the departments of Lozere, Aveyron, Card, Herault, Lot and Tarn-et-Garonne. They are of limestone formation, dry, sterile and treeless. These characteristics are most marked in the east of the region, where the Causse de Sauveterre, the Causse Mejan, the Causse Noir and the Larzac flank the Cevennes. Here the Causse Mejan, the most deserted and arid of all, reaches an altitude of nearly 4200 ft. Towards the west the lesser causses of Rouergue and Quercy attain respectively 2950 ft. and 1470 ft. Once an uninterrupted table-land, the causses are now isolated from one another by deep rifts through which run the Tarn, the Dourbie, the Jonte and other rivers. The summits are destitute of running water, since the rain as it falls either sinks through the permeable surface soil or runs into the fissures and chasms, some of great depth, which are peculiar to the region. The inhabitants (_Caussenards_) of the higher causses cultivate hollows in the ground which are protected from the violent winds, and the scanty herbage permits of the raising of sheep, from the milk of which Roquefort cheeses are made. In the west, where the rigours of the weather are less severe, agriculture is more easily carried on.

CAUSSIN DE PERCEVAL, ARMAND-PIERRE (1795-1871), French orientalist, was born in Paris on the 13th of January 1795. His father, Jean Jacques Antoine Caussin de Perceval (1759-1835), was professor of Arabic in the College de France. In 1814 he went to Constantinople as a student interpreter, and afterwards travelled in Asiatic Turkey, spending a year with the Maronites in the Lebanon, and finally becoming dragoman at Aleppo. Returning to Paris, he became professor of vulgar Arabic in the school of living Oriental languages in 1821, and also professor of Arabic in the College de France in 1833. In 1849 he was elected to the Academy of Inscriptions. He died at Paris during the siege on the 15th of January 1871.

Caussin de Perceval published (1828) a useful _Grammaire arabe vulgaire_, which passed through several editions (4th ed., 1858), and edited and enlarged Elie Bocthor's[1] _Dictionnaire francais-arabe_ (2 vols., 1828; 3rd ed., 1864); but his great reputation rests almost entirely on one book, the _Essai sur l'histoire des Arabes avant l'Islamisme, pendant l'epoque de Mahomet_ (3 vols., 1847-1849), in which the native traditions as to the early history of the Arabs, down to the death of Mahommed and the complete subjection of all the tribes to Islam, are brought together with wonderful industry and set forth with much learning and lucidity. One of the principal MS. sources used is the great _Kitab al-Aghani_ (Book of Songs) of Abu Faraj, which has since been published (20 vols., Boulak, 1868) in Egypt; but no publication of texts can deprive the _Essai_, which is now very rare, of its value as a trustworthy guide through a tangled mass of tradition.

CAUSTIC (Gr. [Greek: kaustikos], burning), that which burns. In surgery, the term is given to substances used to destroy living tissues and so inhibit the action of organic poisons, as in bites, malignant disease and gangrenous processes. Such substances are silver nitrate (lunar caustic), the caustic alkalis (potassium and sodium hydrates), zinc chloride, an acid solution of mercuric nitrate, and pure carbolic acid. In mathematics, the "caustic surfaces" of a given surface are the envelopes of the normals to the surface, or the loci of its centres of principal curvature.

In optics, the term _caustic_ is given to the envelope of luminous rays after reflection or refraction; in the first case the envelope is termed a catacaustic, in the second a diacaustic. Catacaustics are to be observed as bright curves when light is allowed to fall upon a polished riband of steel, such as a watch-spring, placed on a table, and by varying the form of the spring and moving the source of light, a variety of patterns may be obtained. The investigation of caustics, being based on the assumption of the rectilinear propagation of light, and the validity of the experimental laws of reflection and refraction, is essentially of a geometrical nature, and as such it attracted the attention of the mathematicians of the 17th and succeeding centuries, more notably John Bernoulli, G.F. de l'Hopital, E.W. Tschirnhausen and Louis Carre.

Caustics by reflection.

The simplest case of a caustic curve is when the reflecting surface is
a circle, and the luminous rays emanate from a point on the
circumference. If in fig. 1 AQP be the reflecting circle having C as
centre, P the luminous point, and PQ any incident ray, and we join CQ
it follows, by the law of the equality of the angles of incidence and
reflection, that the reflected ray QR is such that the angles RQC and
CQP are equal; to determine the caustic, it is necessary to determine
the envelope of this line. This may be readily accomplished
geometrically or analytically, and it will be found that the envelope
is a cardioid (q.v.), i.e. an epicycloid in which the radii of the
fixed and rolling circles are equal. When the rays are parallel, the
reflecting surface remaining circular, the question can be similarly
treated, and it is found that the caustic is an epicycloid in which
the radius of the fixed circle is twice that of the rolling circle
(fig. 2). The geometrical method is also applicable when it is
required to determine the caustic after any number of reflections at a
spherical surface of rays, which are either parallel or diverge from a
point on the circumference. In both cases the curves are epicycloids;
in the first case the radii of the rolling and the fixed circles are
a(2n - 1)/4n and a/2n, and in the second, an/(2n + 1) and a/(2n + 1),
where a is the radius of the mirror and n the number of reflections.

]

The Cartesian equation to the caustic produced by reflection at a
circle of rays diverging from any point was obtained by Joseph Louis
Lagrange; it may be expressed in the form

{(4c^2 - a^2)(x^2 + y^2) - 2a^2 cx - a^2 c^2 }^3 =
= 27a^4 c^2 y^2 (x^2 + y^2 - c^2)^2,

where a is the radius of the reflecting circle, and c the distance of
the luminous point from the centre of the circle. The polar form is
{(u + p) cos 1/2[theta]}^2/3 + {(u - p) sin 1/2[theta]}^2/3 = (2k)^2/3,
where p and k are the reciprocals of c and a, and u the reciprocal of
the radius vector of any point on the caustic. When c = a or = [oo]
the curve reduces to the cardioid or the two cusped epicycloid
previously discussed. Other forms are shown in figs. 3, 4, 5, 6. These
curves were traced by the Rev. Hammet Holditch (_Quart. Jour. Math._
vol. i.).

_Secondary caustics_ are orthotomic curves having the reflected or
refracted rays as normals, and consequently the proper caustic curve,
being the envelope of the normals, is their evolute. It is usually the
case that the secondary caustic is easier to determine than the
caustic, and hence, when determined, it affords a ready means for
deducing the primary caustic. It may be shown by geometrical
considerations that the secondary caustic is a curve similar to the
first positive pedal of the reflecting curve, of twice the linear
dimensions, with respect to the luminous point. For a circle, when the
rays emanate from any point, the secondary caustic is a limacon, and
hence the primary caustic is the evolute of this curve.

Caustics by refraction.

The simplest instance of a caustic by refraction (or diacaustic) is
when luminous rays issuing from a point are refracted at a straight
line. It may be shown geometrically that the secondary caustic, if the
second medium be less refractive than the first, is an ellipse having
the luminous point for a focus, and its centre at the foot of the
perpendicular from the luminous point to the refracting line. The
evolute of this ellipse is the caustic required. If the second medium
be more highly refractive than the first, the secondary caustic is a
hyperbola having the same focus and centre as before, and the caustic
is the evolute of this curve. When the refracting curve is a circle
and the rays emanate from any point, the locus of the secondary
caustic is a Cartesian oval, and the evolute of this curve is the
required diacaustic. These curves appear to have been first discussed
by Gergonne. For the caustic by refraction of parallel rays at a
circle reference should be made to the memoirs by Arthur Cayley.

REFERENCES.--Arthur Cayley's "Memoirs on Caustics" in the _Phil.
Trans._ for 1857, vol. 147, and 1867, vol. 157, are especially to be
consulted. Reference may also be made to R.S. Heath's _Geometrical
Optics_ and R.A. Herman's _Geometrical Optics_ (1900).

FOOTNOTE:

[1] Elie Bocthor (1784-1821) was a French orientalist of Coptic
origin. He was the author of a _Traite des conjugaisons_ written in
Arabic, and left his Dictionary in MS.

CAUTERETS, a watering-place of south-western France in the department of Hautes-Pyrenees, 20 m. S. by W. of Lourdes by rail. Pop. (1906) 1030. It lies in the beautiful valley of the Gave de Cauterets, and is well known for its copious thermal springs. They are chiefly characterized by the presence of sulphur and silicate of soda, and are used in the treatment of diseases of the respiratory organs, rheumatism, skin diseases and many other maladies. Their temperature varies between 75 deg. and 137 deg. F. The springs number twenty-four, and there are nine bathing establishments. Cauterets is a centre for excursions, the Monne (8935 ft.), the Cabaliros (7655 ft.), the Pic de Chabarrou (9550 ft.), the Vignemale (10,820 ft.), and other summits being in its neighbourhood.

CAUTIN, a province of southern Chile, bounded N. by Arauco, Malleco and Bio-Bio, E. by Argentina, S. by Valdivia, and W. by the Pacific. Its area is officially estimated at 5832 sq. m. Cautin lies within the temperate agricultural and forest region of the south, and produces wheat, cattle, lumber, tan-bark and fruit. The state central railway from Santiago to Puerto Montt crosses the province from north to south, and the Cautin, or Imperial, and Tolten rivers (the latter forming its southern boundary) cross from east to west, both affording excellent transportation facilities. The province once formed part of the territory occupied by the Araucanian Indians, and its present political existence dates from 1887. Its population (1905) was 96,139, of whom a large percentage were European immigrants, principally Germans. The capital is Temuco, on the Rio Cautin; pop. (1895) 7078. The principal towns besides Temuco are Lautaro (3139) and Nueva Imperial (2179), both of historic interest because they were fortified Spanish outposts in the long struggle with the Araucanians.

CAUTLEY, SIR PROBY THOMAS (1802-1871), English engineer and palaeontologist, was born in Suffolk in 1802. After some years' service in the Bengal artillery, which he joined in 1819, he was engaged on the reconstruction of the Doab canal, of which, after it was opened, he had charge for twelve years (1831-1843). In 1840 he reported on the proposed Ganges canal, for the irrigation of the country between the rivers Ganges, Hindan and Jumna, which was his most important work. This project was sanctioned in 1841, but the work was not begun till 1843, and even then Cautley found himself hampered in its execution by the opposition of Lord Ellenborough. From 1845 to 1848 he was absent in England owing to ill-health, and on his return to India he was appointed director of canals in the North-Western Provinces. After the Ganges canal was opened in 1854 he went back to England, where he was made K.C.B., and from 1858 to 1868 he occupied a seat on the council of India. He died at Sydenham, near London, on the 25th of January 1871. In 1860 he published a full account of the making of the Ganges canal, and he also contributed numerous memoirs, some written in collaboration with Dr Hugh Falconer, to the _Proceedings_ of the Bengal Asiatic Society and the Geological Society of London on the geology and fossil remains of the Sivalik Hills.

CAUVERY, or KAVERI, a river of southern India. Rising in Coorg, high up amid the Western Ghats, in 12 deg. 25' N. lat. and 75 deg. 34' E. long., it flows with a general south-eastern direction across the plateau of Mysore, and finally pours itself into the Bay of Bengal through two principal mouths in Tanjore district. Its total length is 472 m., the estimated area of its basin 27,700 sq.m. The course of the river in Coorg is very tortuous. Its bed is generally rocky; its banks are high and covered with luxuriant vegetation. On entering Mysore it passes through a narrow gorge, but presently widens to an average breadth of 300 to 400 yds. Its bed continues rocky, so as to forbid all navigation; but its banks are here bordered with a rich strip of cultivation. In its course through Mysore the channel is interrupted by twelve anicuts or dams for the purpose of irrigation. From the most important of these, known as the Madadkatte, an artificial channel is led to a distance of 72 m., irrigating an area of 10,000 acres, and ultimately bringing a water-supply into the town of Mysore. In Mysore state the Cauvery forms the two islands of Seringapatam and Sivasamudram, which vie in sanctity with the island of Seringam lower down in Trichinopoly district. Around the island of Sivasamudram are the celebrated falls of the Cauvery, unrivalled for romantic beauty. The river here branches into two channels, each of which makes a descent of about 200 m. in a succession of rapids and broken cascades. After entering the Madras presidency, the Cauvery forms the boundary between the Coimbatore and Salem districts, until it strikes into Trichinopoly district. Sweeping past the historic rock of Trichinopoly, it breaks at the island of Seringam into two channels, which enclose between them the delta of Tanjore, the garden of southern India. The northern channel is called the Coleroon (Kolidam); the other preserves the name of Cauvery. On the seaward face of its delta are the open roadsteads of Negapatam and French Karikal. The only navigation on any portion of its course is carried on in boats of basket-work. It is in the delta that the real value of the river for irrigation becomes conspicuous. This is the largest delta system, and the most profitable of all the works in India. The most ancient irrigation work is a massive dam of unhewn stone, 1080 ft. long, and from 40 to 60 ft. broad, across the stream of the Cauvery proper, which is supposed to date back to the 4th century, is still in excellent repair, and has supplied a model to British engineers. The area of the ancient system was 669,000 acres, the modern about 1,000,000 acres. The chief modern work is the anicut across the Coleroon, 2250 ft. long, constructed by Sir Arthur Cotton between 1836 and 1838. The Cauvery Falls have been utilized for an electric installation, which supplies power to the Kolar gold-mines and light to the city of Mysore.

The Cauvery is known to devout Hindus as Dakshini Ganga, or the Ganges of the south, and the whole of its course is holy ground. According to the legend there was once born upon earth a girl named Vishnumaya or Lopamudra, the daughter of Brahma; but her divine father permitted her to be regarded as the child of a mortal, called Kavera-muni. In order to obtain beatitude for her adoptive father, she resolved to become a river whose waters should purify from all sin. Hence it is that even the holy Ganges resorts underground once in the year to the source of the Cauvery, to purge herself from the pollution contracted from the crowd of sinners who have bathed in her waters.

CAVA DEI TIRRENI, a town and episcopal see of Campania, Italy, in the province of Salerno, 6 m. N.W. by rail from the town of Salerno. Pop. (1901) town, 7611; commune, 23,415. It lies fairly high in a richly cultivated valley, surrounded by wooded hills, and is a favourite resort of foreigners in spring and autumn, and of the Neapolitans in summer. A mile to the south-west is the village of Corpo di Cava (1970 ft.), with the Benedictine abbey of La Trinita della Cava, founded in 1025 by St Alferius. The church and the greater part of the buildings were entirely modernized in 1796. The old Gothic cloisters are preserved. The church contains a fine organ and several ancient sarcophagi. The archives, now national property, include documents and MSS. of great value (e.g. the _Codex Legum Longobardorum_ of 1004) and fine _incunabula_. The abbot is keeper, and also head of a boarding school.

See M. Morcaldi, _Codex Diplomaticus Cavensis_ ( Naples and Milan,
1873-1893).

CAVAEDIUM, in architecture, the Latin name for the central hall or court within a Roman house, of which five species are described by Vitruvius. (1) The _Tuscanicum_ responds to the greater number apparently of those at Pompeii, in which the timbers of the roof are framed together, so as to leave an open space in the centre, known as the compluvium; it was through this opening that all the light was received, not only in the hall itself, but in the rooms round. The rain from the roof was collected in gutters round the compluvium, and discharged from thence into a tank or open basin in the floor called the impluvium. (2) In the _tetrastylon_ additional support was required in consequence of the dimensions of the hall; this was given by columns placed at the four angles of the impluvium. (3) _Corinthian_ is the term given to the species where additional columns were required. (4) In the _displuviatum_ the roofs, instead of sloping down towards the compluvium, sloped outwards, the gutters being on the outer walls; there was still an opening in the roof, and an impluvium to catch the rain falling through. This species of roof, Vitruvius states, is constantly in want of repair, as the water does not easily run away, owing to the stoppage in the rain-water pipes. (5) The _testudinatum_ was employed when the hall was small and another floor was built over it; no example of this type has been found at Pompeii, and only one of the cavaedium displuviatum.

CAVAGNARI, SIR PIERRE LOUIS NAPOLEON (1841-1879), British military administrator, the son of a French general by his marriage with an Irish lady, was born at Stenay, in the department of the Meuse, on the 4th of July 1841. He nevertheless obtained naturalization as an Englishman, and entered the military service of the East India Company. After passing through the college at Addiscombe, he served through the Oudh campaign against the mutineers in 1858 and 1859. In 1861 he was appointed an assistant commissioner in the Punjab, and in 1877 became deputy commissioner of Peshawar and took part in several expeditions against the hill tribes. In 1878 he was attached to the staff of the British mission to Kabul, which the Afghans refused to allow to proceed. In May 1879, after the death of the amir Shere Ali, Cavagnari negotiated and signed the treaty of Gandamak with his successor, Yakub Khan. By this the Afghans agreed to admit a British resident at Kabul, and the post was conferred on Cavagnari, who also received the Star of India and was made a K.C.B. He took up his residence in July, and for a time all seemed to go well, but on the 3rd of September Cavagnari and the other European members of the mission were massacred in a sudden rising of mutinous Afghan troops. (See AFGHANISTAN.)

CAVAIGNAC, JEAN BAPTISTE (1762-1829), French politician, was born at Gourdon (Lot). He was sent by his department as deputy to the Convention, where he associated himself with the party of the Mountain and voted for the death of Louis XVI. He was constantly employed on missions in the provinces, and distinguished himself by his rigorous repression of opponents of the revolution in the departments of Landes, Basses-Pyrenees and Gers. With his colleague Jacques Pinet (1754-1844) he established at Bayonne a revolutionary tribunal with authority in the neighbouring towns. Charges of cruelty were preferred against him by a local society before the Convention in 1795, but were dismissed. He had represented the Convention in the armies of Brest and of the Eastern Pyrenees in 1793, and in 1795 he was sent to the armies of the Moselle and the Rhine. He filled various minor administrative offices, and in 1806 became an official at Naples in Murat's government. During the Hundred Days he was prefect of the Somme. At the restoration he was proscribed as a regicide, and spent the last years of his life at Brussels, where he died on the 24th of March 1829. His second son was General Eugene Cavaignac (q.v.).

The eldest son, ELEONORE LOUIS GODEFROI CAVAIGNAC (1801-1845), was, like his father, a republican of the _intransigeant_ type. He was bitterly disappointed at the triumph of the monarchical principle after the revolution of July 1830, in which he had taken part. He took part in the Parisian risings of October 1830, 1832 and 1834. On the third occasion he was imprisoned, but escaped to England in 1835. When he returned to France in 1841 he worked on the staff of _La Reforme_, and carried on an energetic republican propaganda. In 1843 he became president of the Society of the Rights of Man, of which he had been one of the founders in 1832. He died on the 5th of May 1845. The recumbent statue (1847) of Godefroi Cavaignac on his tomb at Montmartre (Paris) is one of the masterpieces of the sculptor Francois Rude.

Jean Baptiste's brother, JACQUES-MARIE, VICOMTE CAVAIGNAC (1773-1855), French general, served with distinction in the army under the republic and successive governments. He commanded the cavalry of the XI. corps in the retreat from Moscow, and eventually became Vicomte Cavaignac and inspector-general of cavalry.

CAVAIGNAC, LOUIS EUGENE (1802-1857), French general, son of J.B. Cavaignac, was born at Paris on the 15th of October 1802. After going through the usual course of study for the military profession, he entered the army as an engineer officer in 1824, and served in the Morea in 1828, becoming captain in the following year. When the revolution of 1830 broke out he was stationed at Arras, and was the first officer of his regiment to declare for the new order of things. In 1831 he was removed from active duty in consequence of his declared republicanism, but in 1832 he was recalled to the service and sent to Algeria. This continued to be the main sphere of his activity for sixteen years, and he won especial distinction in his fifteen months' command of the exposed garrison of Tlemcen, a command for which he was selected by Marshal Clausel (1836-1837), and in the defence of Cherchel (1840). Almost every step of his promotion was gained on the field of battle, and in 1844 the duc d'Aumale himself asked for Cavaignac's promotion to the rank of _marechal de camp_. This was made in the same year, and he held various district commands in Algeria up to 1848, when the provisional government appointed him governor-general of the province with the rank of general of division. The post of minister of war was also offered to Cavaignac, but he refused it owing to the unwillingness of the government to quarter troops in Paris, a measure which the general held to be necessary for the stability of the new regime. On his election to the National Assembly, however, Cavaignac returned to Paris. When he arrived on the 17th of May he found the capital in an extremely critical state. Several _emeutes_ had already taken place, and by the 22nd of June 1848 a formidable insurrection had been organized. The only course now open to the National Assembly was to assert its authority by force. Cavaignac, first as minister of war and then as dictator, was called to the task of suppressing the revolt. It was no light task, as the national guard was untrustworthy, regular troops were not at hand in sufficient numbers, and the insurgents had abundant time to prepare themselves. Variously estimated at from 30,000 to 60,000 men, well armed and organized, they had entrenched themselves at every step behind formidable barricades, and were ready to avail themselves of every advantage that ferocity and despair could suggest to them. Cavaignac failed perhaps to appreciate the political exigencies of the moment; as a soldier he would not strike his blow until his plans were matured and his forces sufficiently prepared. When the troops at last advanced in three strong columns, every inch of ground was disputed, and the government troops were frequently repulsed, till, fresh regiments arriving, he forced his way to the Place de la Bastille and crushed the insurrection in its headquarters. The contest, which raged from the 23rd to the morning of the 26th of June, was without doubt the bloodiest and most resolute the streets of Paris have ever seen, and the general did not hesitate to inflict the severest punishment on the rebels.

Cavaignac was censured by some for having, by his delay, allowed the insurrection to gather head; but in the chamber he was declared by a unanimous vote to have deserved well of his country. After laying down his dictatorial powers, he continued to preside over the Executive Committee till the election of a regular president of the republic. It was expected that the suffrages of France would raise Cavaignac to that position. But the mass of the people, and especially the rural population, sick of revolution, and weary even of the moderate republicanism of Cavaignac, were anxious for a stable government. Against the five and a half million votes recorded for Louis Napoleon, Cavaignac received only a million and a half. Not without chagrin at his defeat, he withdrew into the ranks of the opposition. He continued to serve as a representative during the short remainder of the republic. At the _coup d'etat_ of the 2nd December 1851 he was arrested along with the other members of the opposition; but after a short imprisonment at Ham he was released, and, with his newly-married wife, lived in retirement till his death, which took place at Ourne (Sarthe) on the 28th of October 1857.

His son, JACQUES MARIE EUGENE GODEFROI CAVAIGNAC (1853-1905), French politician, was born in Paris on the 21st of May 1853. He made public profession of his republican principles as a schoolboy at the Lycee Charlemagne by refusing in 1867 to receive a prize at the Sorbonne from the hand of the prince imperial. He received the military medal for service in the Franco-Prussian War, and in 1872 entered the Ecole Polytechnique. He served as a civil engineer in Angouleme until 1881, when he became master of requests in the council of state. In the next year he was elected deputy for the arrondissement of Saint-Calais (Sarthe) in the republican interest. In 1885-1886 he was under-secretary for war in the Henri Brisson ministry, and he served in the cabinet of Emile Loubet (1892) as minister of marine and of the colonies. He had exchanged his moderate republicanism for radical views before he became war minister in the cabinet of Leon Bourgeois (1895-1896). He was again minister of war in the Brisson sabinet in July 1898, when he read in the chamber a document which definitely incriminated Captain Alfred Dreyfus. On the 30th of August, however, he stated that this had been discovered to be a forgery by Colonel Henry, but he refused to concur with his colleagues in a revision of the Dreyfus prosecution, which was the logical outcome of his own exposure of the forgery. Resigning his portfolio, he continued to declare his conviction of Dreyfus's guilt, and joined the Nationalist group in the chamber, of which he became one of the leaders. He also was an energetic supporter of the Ligue de la Patrie Francaise. In 1899 Cavaignac was an unsuccessful candidate for the presidency of the republic. He had announced his intention of retiring from political life when he died at his country-seat near Flee (Sarthe) on the 25th of September 1905. He wrote an important book on the _Formation de la Prusse contemporaine_ (2 vols., 1891-1898), dealing with the events of 1806-1813.

CAVAILLON, a town of south-eastern France in the department of Vaucluse, 20 m. S.E. of Avignon by rail. Pop. (1906) town, 5760; commune, 9952. Cavaillon lies at the southern base of Mont St Jacques on the right bank of the Durance above its confluence with the Coulon. It has a hotel de ville of the 18th century, a church of the 12th century, dedicated to St Veran, and the mutilated remains of a triumphal arch of the Roman period. The town is an important railway junction and the commercial centre of a rich and well-irrigated plain, which produces melons and other fruits, early vegetables (artichokes, tomatoes, celery, potatoes), and other products in profusion. Silk-worms are reared, and silk is an important article of trade. The preparation of preserved vegetables, fruits and other provisions, distilling, and the manufacture of straw hats and leather are carried on. Numerous minor relics of the Roman period have been found to the south of the present town, on the site of the ancient _Cabellio_, a place of some note in the territory of the Cavares. In medieval and modern history the town has for the most part followed the fortunes of the Comtat Venaissin, in which it was included. Till the time of the Revolution it was the see of a bishop, and had a large number of monastic establishments.

CAVALCANTI, GUIDO (c. 1250-1300), Italian poet and philosopher, was the son of a philosopher whom Dante, in the _Inferno_, condemns to torment among the Epicureans and Atheists; but he himself was a friend of the great poet. By marriage with Beatrice, daughter of Farinata Uberti, he became head of the Ghibellines; and when the people, weary of continual brawls, aroused themselves, and sought peace by banishing the leaders of the rival parties, he was sent to Sarzana, where he caught a fever, of which he died. Cavalcanti has left a number of love sonnets and canzoni, which were honoured by the praise of Dante. Some are simple and graceful, but many are spoiled by a mixture of metaphysics borrowed from Plato, Aristotle and the Christian Fathers. They are mostly in honour of a French lady, whom he calls Mandetta. His _Canzone d'Amore_ was extremely popular, and was frequently published; and his complete poetical works are contained in Giunti's collection (Florence, 1527; Venice, 1531-1532). He also wrote in prose on philosophy and oratory.

See D.G. Rossetti, _Dante and his Circle_ (1874).

CAVALIER, JEAN (1681-1740), the famous chief of the Camisards (q.v.), was born at Mas Roux, a small hamlet in the commune of Ribaute near Anduze (Gard), on the 28th of November 1681. His father, an illiterate peasant, had been compelled by persecution to become a Roman Catholic along with his family, but his mother brought him up secretly in the Protestant faith. In his boyhood he became a shepherd, and about his twentieth year he was apprenticed to a baker. Threatened with prosecution for his religious opinions he went to Geneva, where he passed the year 1701; he returned to the Cevennes on the eve of the rebellion of the Camisards, who by the murder of the Abbe du Chayla at Pont-de-Monvert on the night of the 24th of July 1702 raised the standard of revolt. Some months later he became their leader. He showed himself possessed of an extraordinary genius for war, and Marshal Villars paid him the high compliment of saying that he was as courageous in attack as he was prudent in retreat, and that by his extraordinary knowledge of the country he displayed in the management of his troops a skill as great as that of the ablest officers. Within a period of two years he was to hold in check Count Victor Maurice de Broglie and Marshal Montrevel, generals of Louis XIV., and to carry on one of the most terrible partisan wars in French history.

He organized the Camisard forces and maintained the most severe discipline. As an orator he derived his inspiration from the prophets of Israel, and raised the enthusiasm of his rude mountaineers to a pitch so high that they were ready to die with their young leader for the sake of liberty of conscience. Each battle increased the terror of his name. On Christmas day 1702 he dared to hold a religious assembly at the very gates of Alais, and put to flight the local militia which came forth to attack him. At Vagnas, on the 10th of February 1703, he routed the royal troops, but, defeated in his turn, he was compelled to find safety in flight. But he reappeared, was again defeated at Tour de Bellot (April 30), and again recovered himself, recruits flocking to him to fill up the places of the slain. By a long series of successes he raised his reputation to the highest pitch, and gained the full confidence of the people. It was in vain that more rigorous measures were adopted against the Camisards. Cavalier boldly carried the war into the plain, made terrible reprisals, and threatened even Nimes itself. On the 16th of April 1704 he encountered Marshal Montrevel himself at the bridge of Nages, with 1000 men against 5000, and, though defeated after a desperate conflict, he made a successful retreat with two-thirds of his men. It was at this moment that Marshal Villars, wishing to put an end to the terrible struggle, opened negotiations, and Cavalier was induced to attend a conference at Pont d'Avene near Alais on the 11th of May 1704, and on the 16th of May he made submission at Nimes. These negotiations, with the proudest monarch in Europe, he carried on, not as a rebel, but as the leader of an army which had waged an honourable war. Louis XIV. gave him a commission as colonel, which Villars presented to him personally, and a pension of 1200 livres. At the same time he authorized the formation of a Camisard regiment for service in Spain under his command.

Before leaving the Cevennes for the last time he went to Alais and to Ribaute, followed by an immense concourse of people. But Cavalier had not been able to obtain liberty of conscience, and his Camisards almost to a man broke forth in wrath against him, reproaching him for what they described as his treacherous desertion. On the 21st of June 1704, with a hundred Camisards who were still faithful to him, he departed from Nimes and came to Neu-Brisach (Alsace), where he was to be quartered. From Dijon he went on to Paris, where Louis XIV. gave him audience and heard his explanation of the revolt of the Cevennes. Returning to Dijon, fearing to be imprisoned in the fortress of Neu-Brisach, he escaped with his troop near Montbeliard and took refuge at Lausanne. But he was too much of a soldier to abandon the career of arms. He offered his services to the duke of Savoy, and with his Camisards made war in the Val d'Aosta. After the peace he crossed to England, where he formed a regiment of refugees which took part in the Spanish expedition under the earl of Peterborough and Sir Cloudesley Shovel in May 1705. At the battle of Almansa the Camisards found themselves opposed to a French regiment, and without firing the two bodies rushed one upon the other. Cavalier wrote later (July 10, 1707): "The only consolation that remains to me is that the regiment I had the honour to command never looked back, but sold its life dearly on the field of battle. I fought as long as a man stood beside me and until numbers overpowered me, losing also an immense quantity of blood from a dozen wounds which I received." Marshal Berwick never spoke of this tragic event without visible emotion.

On his return to England a small pension was given him and he settled at Dublin, where he published _Memoirs of the Wars of the Cevennes under Col. Cavalier_, written in French and translated into English with a dedication to Lord Carteret (1726). Though Cavalier received, no doubt, assistance in the publication of the Memoirs, it is none the less true that he provided the materials, and that his work is the most valuable source for the history of his life. He was made a general on the 27th of October 1735, and on the 25th of May 1738 was appointed lieutenant-governor of Jersey. Writing in the following year (August 26, 1739) he says: "I am overworked and weary; I am going to take the waters in England so as to be in a fit condition for the war against the Spaniards if they reject counsels of prudence." He was promoted to the rank of major-general on the 2nd of July 1739, and died in the following year. In the parochial register of St Luke's, Chelsea, there is an entry: "Burial A.D. 1740, May 18, Brigadier John Cavalier."

There is a story which represents him as the fortunate rival of Voltaire for the hand of Olympe, daughter of Madame Dunoyer, author of the _Lettres galantes_. During his stay in England he married the daughter of Captain de Ponthieu and Marguerite de la Rochefoucauld, refugees living at Portarlington. Malesherbes, the courageous defender of Louis XVI., bears the following eloquent testimony to this young hero of the Cevennes:--"I confess," he says, "that this warrior, who, without ever having served, found himself by the mere gift of nature a great general,--this Camisard who was bold to punish a crime in the presence of a fierce troop which maintained itself by little crimes--this coarse peasant who, when admitted at twenty years of age into the society of cultivated people, caught their manners and won their love and esteem, this man who, though accustomed to a stormy life, and having just cause to be proud of his success, had yet enough philosophy in him by nature to enjoy for thirty-five years a tranquil private life--appears to me to be one of the rarest characters to be found in history."

For a more detailed account see F. Puaux, _Vie de Jean Cavalier_
(1868); David C.A. Agnew, _Protestant Exiles from France_, ii. 54-66
(Lond., 1871); Charvey, _Jean Cavalier: nouveaux documents inedits_
(1884). Eugene Sue popularized the name of the Camisard chief in _Jean
Cavalier ou les fanatiques des Cevennes_ (1840). (F. Px.)

CAVALIER, a horseman, particularly a horse-soldier or one of gentle birth trained in knightly exercises. The word is taken from one of the French words which derived ultimately from the Late Lat. _caballarius_, a horseman, from Lat. _caballus_, properly a pack-horse, which gave the Fr. _cheval._ a _chevalier_. This last word is the regular French for "knight," and is chiefly used in English for a member of certain foreign military or other orders, particularly of the Legion of Honour. Cavalier in English was early applied in a contemptuous sense to an overbearing swashbuckler--a roisterer or swaggering gallant. In Shakespeare (_2 Henry IV._ v. iii. 62) Shallow calls Bardolph's companions "cavaleros." "Cavalier" is chiefly associated with the Royalists, the supporters of Charles I. in the struggle with the Parliament in the Great Rebellion. Here again it first appears as a term of reproach and contempt, applied by the opponents of the king. Charles in the _Answer to the Petition_ (June 13, 1642) speaks of cavaliers as a "word by what mistake soever it seemes much in disfavour." Further quotations of the use of the word by the Parliamentary party are given in the _New English Dictionary_. It was soon adopted (as a title of honour) by the king's party, who in return applied Roundhead to their opponents, and at the Restoration the court party preserved the name, which survived till the rise of the term Tory (see WHIG AND TORY). The term "cavalier" has been adopted from the French as a term in fortification for a work of great command constructed in the interior of a fort, bastion or other defence, so as to fire over the main parapet without interfering with the fire of the latter. A greater volume of fire can thus be obtained, but the great height of the cavalier makes it an easy target for a besieger's guns.

CAVALIERE, EMILIO DEL, 16th-century Italian musical composer, was born in Rome about 1550 of a noble family. He held a post at the court of Ferdinand I. of Tuscany from 1588 to 1597, and during his residence at Florence was on terms of intimacy with J. Peri, O. Rinuccini, G. Caccini and the rest of the Bardi circle. In 1597 he returned to Rome, and became connected with the Congregation of the Oratory founded by St Philip Neri. Here in 1600 was performed Cavaliere's contribution to the musical reformation initiated by his circle of friends in Florence--_La Rappresentazione di Anima e di Corpo_, a sacred drama, which is regarded as the first example of what is now called oratorio. It is generally supposed that he was no longer living when the work was performed, but some authorities assign 1602 as the date of his death.

Cavaliere's style is more facile than that of Peri and Caccini, but he is inferior to them in depth of musical expression. He is, however, important as being the first to apply the new monodic style to sacred music, and as the founder of the Roman school of the 17th century which included Mazzocchi, Carissimi and Alessandro Scarlatti.

See also H. Goldschmidt, _Studien zur Geschichte der italienischen
Oper im 17. Jahrhundert_, Band i.

CAVALLI, FRANCESCO (1599?-1676), Italian musical composer, was born at Crema in 1599 or 1600. His real name was Pier Francesco Caletti-Bruni, but he is better known by that of Cavalli, the name of his patron, a Venetian nobleman. He became a singer at St Mark's in Venice in 1617, second organist in 1639, first organist in 1665, and in 1668 _maestro di cappella_. He is, however, chiefly important for his operas. He began to write for the stage in 1639 (_Le Nozze di Teti e di Peleo_), and soon established so great a reputation that he was summoned to Paris in 1660 to produce an opera (_Serse_) at the Louvre in honour of the marriage of Louis XIV. He visited Paris again in 1662, bringing out his _Ercole Amante_. His death occurred in Venice on the 14th of January 1676. Twenty-seven operas of Cavalli are still extant, most of them being preserved in the library of St Mark at Venice. Monteverde had found opera a musico-literary experiment, and left it a magnificent dramatic spectacle. Cavalli succeeded in making opera a popular entertainment. He reduced Monteverde's extravagant orchestra to more practical limits, introduced melodious arias into his music and popular types into his _libretti_. His operas have all the characteristic exaggerations and absurdities of the 17th century, but they have also a remarkably strong sense of dramatic effect as well as a great musical facility, and a grotesque humour which was characteristic of Italian grand opera down to the death of Alessandro Scarlatti.

CAVALLINI, PIETRO (c. 1259-1344), Italian painter, born in Rome, was an artist of the earliest epoch of the modern Roman school, and was taught painting and mosaic by Giotto while employed at Rome; it is believed that he assisted his master in the mosaic of the Navicella or ship of St Peter, in the porch of the church of that saint. He also studied under the Cosmati. Lanzi describes him as an adept in both arts, and mentions with approbation his grand fresco of a Crucifixion at Assisi, still in tolerable preservation; he was, moreover, versed in architecture and in sculpture. According to George Vertue, it is highly probable that Cavallini executed, in 1279, the mosaics and other ornaments of the tomb of Edward the Confessor in Westminster Abbey. He would thus be the "Petrus Civis Romanus" whose name is inscribed on the shrine; but a comparison of dates invalidates this surmise. He died in 1344, at the age of eighty-five, in the odour of sanctity, having in his later years been a man of eminent piety. He is said to have carved for the Basilica of San Paolo fuori le Mura, close to Rome, a crucifix which spoke in 1370 to a female saint. Some highly important works by Cavallini in the church of Santa Cecilia in Trastevere, Rome, have been recently discovered.

CAVALLO, TIBERIUS (1749-1809), Anglo-Italian electrician and natural philosopher, was born on the 30th of March 1749 at Naples, where his father was a physician. In 1771 he came to England with the intention of pursuing a mercantile career, but he soon turned his attention to scientific work. Although he made several ingenious improvements in scientific instruments, his mind was rather imitative and critical than creative. He published numerous works on different branches of physics, including _A Complete Treatise on Electricity_ (1777), _Treatise on the Nature and Properties of Air and other permanently Elastic Fluids_ (1781), _History and Practice of Aerostation_ (1785), _Treatise on Magnetism_ (1787), _Elements of Natural and Experimental Philosophy_ (1803), _Theory and Practice of Medical Electricity_ (1780), and _Medical Properties of Factitious Air_ (1798). He died in London on the 21st of December 1809.

CAVALLOTTI, FELICE (1842-1898), Italian politician, poet and dramatic author, was born at Milan on the 6th of November 1842. In 1860 and 1866 he fought with the Garibaldian Corps, but first attained notoriety by his anti-monarchical lampoons in the _Gazzetta di Milano_ and in the _Gazzettina Rosa_ between 1866 and 1872. Elected to parliament as deputy for Corteolona in the latter year, he took the oath of allegiance after having publicly impugned its validity. Eloquence and turbulent, combativeness in and out of parliament secured for him the leadership of the extreme Left on the death of Bertani in 1886. During his twelve years' leadership his party increased in number from twenty to seventy, and at the time of his death his parliamentary influence was greater than ever before. Though ambitious and addicted to defamatory methods of personal attack which sometimes savoured of political blackmail, Cavallotti's eloquent advocacy of democratic reform, and apparent generosity of sentiment, secured for him a popularity surpassed by that of no contemporary save Crispi. Services rendered in the cholera epidemic of 1885, his numerous lawsuits and thirty-three duels, his bitter campaign against Crispi, and his championship of French interests, combined to enhance his notoriety and to increase his political influence. By skilful alliances with the marquis di Rudini he more than once obtained practical control of the Italian government, and exacted notable concessions to Radical demands. He was killed on the 6th of March 1898 in a duel with Count Macola, editor of the conservative _Gazetta di Venezia_, whom he had assailed with characteristic intemperance of language. By his death the house of Savoy lost a relentless foe, and the revolutionary elements in Italy a gifted, if not entirely trustworthy, leader. (H. W. S.)

CAVALRY (Fr. _cavalerie_, Ger. _Kavallerie_ or _Reiterei_, derived ultimately from late Lat. _caballus_, horse), a word which came into use in military literature about the middle of the 16th century as applied to mounted men of all kinds employed for combatant purposes, whether intended primarily for charging in masses, in small bodies, or for dismounted fighting. By degrees, as greater refinement of terminology has become desirable, the idea has been narrowed down until it includes only "horsemen trained to achieve the purpose of their commander by the combined action of man and horse," and this definition will be found to cover the whole field of cavalry activity, from the tasks entrusted to the cavalry "corps" of 10,000 sabres down to the missions devolving on isolated squadrons and even troops.

Early use of mounted warriors.

_History_--The evolution of the cavalry arm has never been uniform at any one time over the surface of the globe, but has always been locally modified by the conditions of each community and the stage of intellectual development to which at any given moment each had attained. The first condition for the existence of the arm being the existence of the horse itself, its relative scarcity or the reverse and its adaptability to its environment in each particular district have always exercised a preponderating influence on the development of cavalry organization and tactics. The indigenous horses of Europe and Asia being very small, the first application of their capabilities for war purposes seems everywhere to have been as draught animals for chariots, the construction of which implies not only the existence of level surfaces, perhaps of actual roads, but a very considerable degree of mechanical skill in those who designed and employed them. The whole of the classical and Oriental mythologies, together with the earliest monuments of Egypt, Assyria and India, are convincing on this point. Nowhere can we find a trace either of description or delineation of animals physically capable of carrying on their backs the armed men of the period. All the earliest allusions to the use of the horse in war either point directly to the employment as a draught animal, or where not specific, as in the description of the war-horse in Job, they would apply equally well to one harnessed to a chariot as to one ridden under the saddle.