DESCENDANTS 



DKHKItT 



773 



mi-lit, In' >liu\\i-,| how to express the nature and tin? 



pro|>rllil-. n|" i-VI-IA CIIIAC, ll\ lltl equation I..-1 \\.-.-ll 



t\\<> v;u i.-ilili ordinaten ; thus, in fact, originating 



Analytical Geometry, which has led to the brightest 

 disco\ .! I.-*. Edition-^ oi Descartes' collected works 

 were published in Latin in Iti'JT and I71.'<, ami in 

 French by Cousin in l.S'Jl -Jo. His chief philo- 

 !-o|iliiciil works have IM-I-II translated into English 

 by Professor Yeitch. See Millet, 1^ < Vie, 



se* Trtirniu; .%* I >, it rertei (2 vols. 18(17-71); 

 Kiino Fischer, Descartes and his School ( Eng. trans. 

 1887); and English works by W. Cunningham 

 (1877), Lowndes (1878), Mahaliy (1880), and Mar- 

 tineau (1885). 



Descendants. See HEIR, CONSANGUINITY, 

 l'i:nh.i;i:i:, SITCKSSION. 



Descent of .11 an. See MAN, DARWINIAN 

 THKOISV. 



Deschainps EUSTACHE, a French poet, who 

 was born at Vertus, in Champagne, in 1328. He 

 was educated at Orleans University, and was in 

 the course of his life a soldier, a magistrate, a court 

 favourite, ami a traveller in Italy and Hungary. 

 He held several important post* in his native pro- 

 vince, but his possessions were ravaged by the 

 English, and he seems to have been a poor man 

 when he died in 1415. He was lx>th a popular and 

 voluminous writer. He composed \\15ballades, a 

 multitude of rondeaiix, virelais, and other lyrics, 

 besides a long poem of 13,000 lines, entitled the 

 Miroir de Mariaqthfa works in all amounting to 

 more than 100,000 lines. Deschainps was an ardent 

 patriot, in whose verse hatred of the English and 

 of the native oppressors of the French poor finds 

 repeated and bitter expression, and' his style is as 

 a rule somewhat wanting in elegance and ease. 

 Occasionally, as in his lament for Du Guesdin, 

 his verse is both graceful and touching ; and in 

 one at least of his pieces, an apologue exposing the 

 exactions of the rich, he gives proof of a grim and 

 trenchant satiric faculty. The edition of his Potties 

 Morales, edited by M. Cropelet (1832), is superseded 

 by the complete edition for the Old French Text 

 Society by the Marquis de Queux de Saint-Hilaire 

 (1878-95). See the monograph by Sarradin (1878), 

 ami Besant's Early French, Poets ( 1868). 



Deseret, the name first adopted by the Mormons 

 for what is now Utah. See MORMONS, L'TAH. 



Desert (literally, ' a solitary place ') is the geo- 

 graphical name applied to a barren and uninhabit- 

 able portion of the earth's surface. Four classes of 

 desert may be distinguished. 



( 1 ) Ice-wastes occupy the central plateau of Green- 

 land, the islands of the Arctic Sea, and proliably 

 the entire Antarctic continent. The ground is 

 covered to an unknown depth by a vast ice-cap, 

 rough and hummocky on the surface, and moving 

 outwards to the coasts in a continual procession of 

 glaciers. 



(2) Tundras are flat plains, little elevated above 

 sea-level, fringing the Arctic shores of the northern 

 continents, and specially characteristic in Siberia 

 (q.v. ). The soil remains frozen to a great depth all 

 the year round, thawing MpwMlulj when the 

 snow melts in summer, and becoming covered with 

 coarse moss and dwarfed Arctic plants. 



(3) Arid wastes, or deserts in the popular sense 

 of the word, occur mainly in two zones encircling 

 the world, and corresponding to regions of minimum 

 rainfall (see CLIMATE). The more extensive ex- 

 tends from near the equator in an east-north-east 

 direction across the whole breadth of North Africa, 

 as i lie Great Sahara, Libyan and Nubian deserts, 

 over the peninsula of Arabia, through Persia, 

 Turkestan, the Gobi or Sliaino Desert, in about 

 52 N. lat., to the Pacific Ocean (see ASIA). 

 The great Indian Desert in the Punjab is the 



only extension of thi belt Mouth of the Him* 

 lava*. The ring i* completed bv the Great 

 Itaftin of North Ann-rim in 40 N. lt. Tba 

 Houtlii-rn /mil-, Irs* complete, conipruies the KnJa 

 hari IWi-rt in south- west Africa, the interior of 

 \>: -t i alia, and small district* in the Argentine 

 !;]. ulili'- and in the Andes. Deceit* occur at all 

 elevations, from considerable deiitlm Itemrath sea- 

 level to many thousand feet above it, and with 

 all varieties of surface, from a Hat PX panne of 

 sand, when- tin- view for day* of travel in bounded 

 by a sharp circle as at sea, to rocky mountain- 

 slopes rent by rough defiles all hare and <-ln<-ll-d 

 by the driving sand. The essential character of an 

 arid waste is it* rainlewoie**, and the scarcity of 

 water on the surface and of water-vapour in the 

 atmosphere. Radiation in the clear air in intense, 

 ami desert climate is consequently of an exagger- 

 ated continental ty|>e. The wind in the Sahara 

 Ix-comes heated to over 150 F. during the day, mid 

 chilled below the freezing-point at night, while the 

 diumal and seasonal extremes in the lofty desert* of 

 Central Asia are much greater. Thus (UMV^NgtOM 

 are most effective in producing land and sea breezes 

 and monsoon winds in consequence of the marked 

 IM-I imlir.-il changes in atmospheric density. Another 

 effect is the Mirage (o.v. ), a phenomenon which, 

 combined with the indescribable horror of loneli- 

 ness that oppresses the occasional traveller, prob- 

 ably accounts for the widespread superstitions 

 peopling deserts, above all other places, with evil 

 and malicious spirits. The dreaded sand-storm 

 or simoom is a kind of tornado or whirl wind 

 which raises the sand in tall rotating columns 

 sweeping over the surface with tremendous velocity. 

 Sand-dunes, sometimes several hundred feet in 

 height, are raised by steady winds, and gradually 

 shift their position, extending the Umnds of the 

 desert to leeward. Desert vegetation is extremely 

 scanty, consisting mainly of hard prickly plants of 

 the cactus, euphorbia, and spinifex kinds, whose 

 glazed surface exhales little of the hardly-won 

 moisture. Animal life is corresjH>ndingly restricted 

 lx)tli in variety and number of individuals. The 

 Camel ( q. v. ) is par excellence the beast of burden 

 for conducting^ traffic across arid wastes. When an 

 overflowing river, such as the Nile, traverses a 

 desert, the land becomes richly fertile in its iminedi. 

 ate neighbourhood, and wherever springs bubble 

 up through the sand there are Oases (q.v.) bearing 

 palm trees and grass. Artificial irrigation, e>|>evi- 

 ally the sinking of artesian wells, has done much to 

 reclaim tracts of desert for agriculture in the Sahara 

 (see ALGERIA), and to a less extent in Australia, 



Geological considerations show that arid deserts 

 are not permanent features of the earth's surface. 

 The mast level expanses have once formed part of 

 the ocean-bed, or at least great inland seas. The 

 orographi>-jil changes which cutoff these Mas and 

 created inland drainage areas probably at the same 

 time modified tin- rainfall of the locality. Exces- 

 sive evaporat ion dried up the great lakes, leaving at 

 present a series of diminishing salt lakes without 

 outlet, receiving rivers which d\\ indie down by 

 evaporation a they How. The onlv commercial 

 commodities yielded by deserts are the salt* (com- 

 mon salt, borax, sodium carbonate, and sometimes 

 sodium nitrate) left in the dried-up lake-beds. 

 These salt lakes are subject to alternate long 

 periods of desiccation and flooding; during the 

 former the area of the desert extends, during the 

 latter it contracts. These period* have been traced 

 out in the case of the Great American lta*in by a 

 series of most interesting researches on the part of 

 the Cnited States Geological Survey. 



(4) Temporary drscrts, or st*pje land*, border 

 tin- Asiatic deserts to the north and west. The 

 saline steppes of the Caspian are true arid wastes ; 



