Why Are Mountain Tops So Cold

There is a story of a squirrel, which, (liscontontod with the cold valley where he had his homo, sot out to roacli a rnountain top, where, thought he, the climate must bc warm and genial, since that spot is so much nearer tlie sun, the greatsource of ln'at. But on reaehing the long-wished-for hcight, he found that although the suu shone with olearer light yet the cold was more intonso than ut the humble home lelt behind. He was well nigh frozen to death, nnd quickly and wisely resolved to return to the valley whé&ce he carne. The process of reasonir.g whicli led poor squin-el into such difficulty and danfcer seems eorreet enough. The only troublc with it is tha-k, liko agreatmany fino spun theories, it does not agree with tho faets in the case. How happens it then that tho nearer we go to the sun, the souroe of heat, the colder we find tho air 'r1 It is beoausc the sun's rays of heat pass through transgaren.t bodiesliko air, without heating them. The heat of tho sun passes direpÜy down through tho air till it strikes t)i! surfaco of tlie carth, wliich is warnied by it. The air becomes warm only by contact with tho warm earth and by the radiation of heat from the earth. But why does not niountaii-tp become warm, mul impait its heat to the sunoundiMgair '- The answer is, that so great is tlie body of cola Mï arotrnd it, in eorapttróon with its om si.v, and k constantly is toe air oroumd it changed by the strong winds that blow therc, that not onough heat oan be accuniulated in tho air to become scnsiKl. . Butwhydoes nut tho uir, wineh is hi a teil by contact with the surfaoo oï the titrth at the luvcl of th sea rísc ti) the mountain-to]s and warnt them up, just the Bame s the héated air in our rooms rises to the oeüing, and niakcs OUI lu "■td# vrarm whilo our foet nro coldï 1$. do thvis rise, indeed; but asitrfsesi! also expands, because it is not so closely pressed by tho suporincumbent air. So by the time it renohos the top of Monnt Woslliington, what was :i single room fiill of corofortably hot air has pxpanded to tl ■ ■ size of a whole ■ liousr.' ; and, as it li:: ceived no moro heat in its Meent, it luis becomo vei'y unconiioxUUy gold. ÍÍÍü heat which was sufficient tö make it feel wann whon it occupiod a gmall space bccomes quite insensible whon it eccpaiuis to a hundrod, or it may be a thoúsand timus the sizo it was before. It is ju t liko a moistened spdnge, frcln whith vu Ier drops when it is squeezed irl the hand, but which appears quite dry when