

PERTURBATIONS 



PKKU 



would describe accurately an ellipse aUmt 

 the earth'* centre an focus, and it* radius-vector 

 would pas* over equal area* in equal times; but 

 only if both boilii- were hoinogeni-ou- uml truly 

 spherical, or had their constituent matter other- 

 wise *o arranged that they might attract each other 

 an if each were collected at Home definite point of 

 iU mas*. The oblatenes* of the earth's ligtirc. there 

 fore, produce* perturbations in what would other- 

 !- be the lixed elliptic orliit of the moon. Again, 

 when we con-ider the sun's action it is obvious that 

 in no position ..I tin- moon can the nun art equally 

 Hi-Hi lih earth and moon ; for at new moon the 

 .11. iii in nearer to the -UM than the earth i-, and 

 i. therefore more attracted (in ptOMrifaa to its 

 man*) than the earth Le. the difference of the 

 sun's action* on the earth ami moon in equivalent 

 to a force tending to draw tin- moon away from 

 the earth. At full moon, on tin- other hand, the 

 earth (in proportion to its maw) is more attracted 

 than the moon is by the .-mi ; and the perturbing 

 influence of the tun is again of the nature of a 

 force tending to separate the earth and moon. 

 About the quartern, again, the sun's attraction 

 (man for mam) U nearly the mime in amount 

 on the earth and moon, but the direction of ita 

 action U not the same on the two bodies, and 

 it U easy to ee that in this cane the perturb- 

 ing force tend* to bring the earth and moon 

 nearer to each other. For any given |>osition of 

 tin- moon, with reference to the earth and sun, 

 the iti/rrrnrr of the accelerating effects of the 

 xiin on the earth and moon if) a disturbing force ; 

 mi'l it i to this that the perturliations of the 

 moon's orliit, which are the most important, and 

 amongRt the most considerable, in the solar system, 

 are due. Bee MOON, PLANETS, &c. 



Peru, a republic of South America, extending 

 from near to IT 2Cf S. lat. Previous t<i the an- 

 ns by < 'liili. the Peruvian i c^,^ ,,. ,,. Md 

 territory stretched southwanl to I ixt i i r.s. b, j. K. 

 -J ln-.'with a length along the I """" "M-- 

 Pacific coaiit of 1400 miles, and a width of 300 

 mil.*. It borders on the Pacific, Ecuador, Brazil, 



Itolivia, and C'hili. The area is roughly estimated 

 at 000,000 sq. in. There ban been no ceii-us since 

 1878, bill the (population i believed to lie stationary 

 owing to infant mortality and other can-. 

 in 1805 stated at 2,730/mo; the aboriginal Inca 

 Indians forming .17 |>errent., the M<-xti:i,.i or half 

 carte* 23 per cent, and the people of pure S|uiiii-h 

 descent, negroes, Chinese, &. .. -jii |>r cent. Peru 

 iartill the country of the Inca people. 



Surface of tike Country. The surface of Peru is 

 extremely varied. It in divideil longitudinally into 

 three well-marked regions. ( 1 ) The ( 'n<ut extends 

 from UM ham of the Andes to the Pacific Ocean, 

 and coni.u of a sandy desert crosned at intervals 

 by riven, along the banks of which then* an- t-ink 

 valley*. (S) The Sierra, or region of the And.-. 

 about rtVi mill", wide, contains t<tii|>endous chains 

 of muuiiUin-. elevateil plains and tableland-, 

 warm ami fertile valleys ami ravines. (3) The 



Muni,,,.,, skirting tl li-tern slopes of the Audi--. 



w the thinl region. It consist* of tropical for.-t- 

 traverwl by great trihutarim of the Vina/on. 

 The coast region has been upraised from the 

 ocean at no very r-mote |-ri.l. The ab nee 

 of rain on this strip of land tietween th- moun- 

 tain* and the sea is caused hy the action of the 

 lofty uplands of the Andes on the trade wind. 



Reaching the now-capped summit* the last iirt id.. 

 of moisture is wrung out of the wind that the very 

 low temperature can extract, and it rushes down 

 to the Pacific coast, cool ami dry. It*. inoi-t,,re i- 

 ,|..|..,t| * . n<iw cm the fc.|.s of the conlillera, and 

 feed* the inuuntain-strmniH which ||,, w ,!,, t<> 

 the coast-valleys. Kn.m NoM-mljer to 



then i- ii-iially con-tnt ilryness on the 

 coast, from June to September the cty i-* ohscured 

 for weeks by mist, sometimes accoiii|uinic<l l.y 

 ilri//.ling rai'n. The maximum temp'ralni. 

 alsnit TH in summer and Hi' in winter. When 

 it i hotte-t anil driest mi the coji-t it is raining 

 heavily in the Amies, and the rivers are full. 

 When" the rivers are lowest ini-ts ami i/<iriinx or 

 ilri/./ling rain* prevail on the couxt. Tlie deserto 

 arc .li\ide<l from each other by forty valleys of 

 great fertility, ami the cultivable area on the coast 

 might lie coiisiilerably extende.) by irrigation. The 

 coast has few protected anchorages, and the head- 

 lands are generally abrupt and lofty. This region 

 is subject to frequent ami seven; earthquakes, the 

 most destructive in modern times having Is-eu 

 that of 1868, which nearly destroyed Arequi|>a 

 and Arica, and that of 1877. Since l.~>7n there have 

 l'en seventy destructive earthquakes recorded on 

 the west coast of South America. 



The Peruvian Andes contain peaks attaining 

 height- of 21,000 and 22,000 feet ; but they have 

 never been measured with scientific accuracy. 

 The mountain-system consists of three chains or 

 irilillrrat. Two of these chains, running parallel 

 and near each other, are of identical origin. The 

 western one is the maritime conlillera and com- 

 prises the volcanoes. The eastern conlillera i 

 magnificent and almost continuous range, in great 

 part of Silurian formation, with clay-slates and 

 eruptive granitic nx-ks. The western cor.lillcra. 

 is cut through by several streams which How into 

 the Pacific, and the eastern conlillera by six tribu- 

 taries of the Amazon, but the central chain U an 

 unbroken water-parting. It consists mainly of 

 crystalline and volcanic rocks, on each side .<f 

 which are strata of aqueous, in great |>art of 

 Jurassic, rocks. The valleys and plateaus between 

 these ranges form the Sierra of Peru, ami include 

 every variety of climate and scenery. They may 

 IH> divided, from a geographical point of view, into 

 four sections, commencing from the north. The 

 first, ,V>O miles long by IIMI broad, comprises the 

 upper liasins of the Maraiion ami lluallaga. The 

 second extends for 200 miles from Cerro Pasco to 

 Ayacucho, including the lake of ('hindmy-eodia 

 and the valley of Jauja. The third extends for 

 J."><| miles to the knot of Viicanota, comprising the 

 up|icr valleys of the Apnrimac, the Vilcainayu, and 

 the Paucartaniho. Here is Cuzco, the capital of 

 the- Ineas, the centre and heart of Peru. The 

 fourth section is the basin of Lake Titicaea, about 

 I.'- 1 ' miles in length and breadth. The lake it -elf 

 i- MI miles long, and 12,545 feet above the level of 

 the sea. A number of rivers, which are of con 

 sidenible volume, during the rainy season, fall into 

 it, and it is drained by the I ie-.ijjuadcro (lowing 

 out of the south-west angle. Hut a great projKir- 

 tion of the water is also taken up by evaiioratioii, 

 and the waters urn gradually receding. Tlie Sierra 

 o f Peru is the original home of the jKitato. Its 

 lofty height -al-o pro. nice s. vcral other edible roots, 

 ami I hi; grain called ,jii',,iiiii (<'/,, /,,,/,!/ in m i/iiiinin . 

 while splendid crops of mai/.e are grown in the 

 valleys. The animals which specially lielong to 

 the Peruvian Sierra an; the domestic llamas and 

 alpacas, ami the wild vicunas. The llamas wire 

 the bfMtaaf burden in the time of the Inca-. cadi 

 carrying a weight of about 100 Ib. Alpacas I 

 always been prized for their long and soft wool, 

 and are tended with great an', Is-ing kept in large 

 HiH'ks. The other animals of the Peruvian Sierra 

 the tonieo or deer, two rodents called i-ismi-im 



and chinchilla, a. native dog, and a fox. The largest. 

 bird is the condor, and tln'ie i-. another bird of the 

 vulture tribe called aleotn-iri. Partridges, called 

 y<". and plovers an- met with on the lofty plateaus. 

 The large and handsome, geese culled &lMeAM and 



