INUNDATION. 725 INVASION. people wei'e killed by such an inundation in the delta of the Ganges and Brahmaputra. Finally, sea waves yeiieraled by earthquake shocks may inundate coastal lamls. These, again, are best illustrated on the low, densely populated coasts of Asia, where earthquake shocks are numerous. The earthi)uake wave, caused by a jar along the seashore or on the sea bottom, disturbs the entire sea from surface to bottom. The wave is dome-shaped, though not very high, perhaps not over an inch or two. But it is so deep and broad that, advancing over the shallow- ing bottom toward the shore, it grows higher and higher, perhaps reaching a height of 100 feet. The wave rushes over the land with ter- rible force and destruetiveness. The earthquake which destroyed Lisbon in 1755 was accompanied by a prodigious tidal wave. By the earthquake wave caused in 1883 during the eruption of Krakatoa in the Strait of Sunda, a water wave was generated which rose from 50 to 80 feet, upon the neighboring lowlands, drowning thou- sands of people, and carrying a large vessel in- land a distance of a mile and a half, leaving it stranded 30 feet above sea-level. By an earth- quake wave, .June 15, 1896, a part of the coast of .Ja])an was devastated for a distance of 175 nules. 27.000 lives were lost, and 00,000 people made lionieless. Many similar instances are on record. Bn!LiOGB.Piiy. VallJs, Btiides sur Ics inonda- iioiis, Iciirs ciiuses et leiirs effcts (Paris, 1857) ; United Ulnlfn Engineci's Report (Washington, 1875) ; Mississippi Iliicr Commission Reports (Washington, 1882-92) ; Montreal Flood Com- mission Report (Montreal, 1890) ; Von Sonklar, ^'on den Veherselnceminunycn (Leipzig, 1883); Work of the Weather ISureuu in Connection mth the Rirers of the United States (Washington, 1S90) ; Stonev, Extraordinari/ Floods in Southern Indiu (London, 1898) : Wiliiams, On Home Ef- fects of Land Floods in n Tidal River (London, 1891); "Storm Waves on the Great Lakes and the Ocean," Monthlij Weather Review (Wash- ington, 1895). INVALIDES, i-ix'vii'lwl', Le.s (Fr.. invalids). Wounilod veterans of the French Army, main- tained at the expense of the State. The Hotel des Invalides is an establishment in Paris where a number of these old soldiers are quartered. The institution was founded by Louis XIV. in 1070. In 1811 it was reorganized; in 1832 its property ■was alienated and the institution made a charge upon the annual budget. The hotel can accom- modate 0000 men. but the actual numlier of in- mates is now much smaller. The dome of the Invalides, in the crypt of which is the tomb of Xajioleon L, is one of the most imposing struc- tires in Paris. INVALIDING (from invalid. Fr. invalide. invalid, from Lat. invalidus. not strong, from in-, not -+- validiis, strong, from ralere, to be strong). In military phraseology, a soldier is said to be invalided when he is sent home from abroad, as a result of climate, wounds, or other causes rendering him unfit for duty. In the X^nited States he would be sent to a general liospital (see IIospnAi.l, where it would be de- cided whether he remained in the army or be returned to civil life. Knglish soldiers are sent to Xetley Hospital for similar treatment and final disposition. INVAKIABLE PLANE. In the solar sys- ti nj, a plane alioul which the planets' (jrbits Jjer- pelually oscillate, deviating from it only to a very small extent on cither side. This plane passes through the centre of gravity of the sofar system, and is so situated that if all the planets be projected on it, and if the mass of each planet be multiplied into the area which is described by the planets' projected radius vector in any as- suuumI unit of time, the sum of such products will be a maximum. By means of this |)ro|H-rty, independent of any particular epoch, it will be easy for astroncnners in future time to <letcrmine the exact position of the plane, and to compare ob.servations together by means of it. Such a plane is not i)eculiar to the solar system, but must exist in all systems where the bodies are acted on by no other force than their mutual attraction. INVARIANT. See Forms. INVASION (Lat. invasio, attack, from in- vudere, to invade, from in, in + vadere, to go, connected with ORG. watan, Ger. leaten, AS. uadan, Eng. wade). The act of entry into an enemy's territory during time of war. In an- cient and medi.Tval times, when an army invaded a country. |)illage, devastation, and slaughter were the rule. It was not until the ar of the Spanish Succession that Marlbonmgh and Villars, by a system of contribution, introduced compara- tive humanity into the conduct of armies. The Prussians and Austrians during the wars of Fred- erick the CJreat were generally deijendcnt upon regularly levied supplies. During the Revolution- ary War, the British Government declared it to be a right of war: (1) to demand provisions and raise contributions, enforceable, if necessary, by the sword: (2) to ravage territory where there was no other way to bring an enemy to engage- ment or terms; (3) to treat all rebels as enemies. The right to ravage has not been asserted or acted upon since by either country, except in the case of the burning of the Capitol and other buildings at Washington by the British in 1814. which was a gross and unjustified violation of the rules of war. Napoleon enforced the principle thst war must pay for war; and after the battle of Jena, the exaction required of Prussia was more than a hundred million francs, while a like contribu- tion was levied upon S])ain in the course of the Peninsdar War. The rights of an invader toward tiie country overrun by hiu> are huge and important, but these rights of belligerent occupation held as confined to the districts actually dominated by the invading force must be carefully distin- guislied from those of conquest. The invaders' military rule in general supersedes the civil authority. In relation to property, a sharp dis- tinction must be drawn between public and pri- vate property. As to the former also the invad- er's rights are held to differ with its character. Thus the contents of the Palatine libraries were carried off to Rome during the Thirty Vears' War. and Xapoleon filled the Louvre Galleries from every capital of F.uropc: but the rule is now well established that ]>uldic money, mili- tary stores, and jiublie buildings are lawful sources of plunder; pidilie estates may be oc- cupied, and the rents and profits therefrom ap- propriated; telegraph and railway property pressed into service, and public edifices interfer- ing with militaiv operations destroyed: but
