Popular Science

Tt is clnimeci that Prof. Bacyer's tneüwl of prodnciiig artificial iudigo I has alleiigth been fomul to bc I meroftUy prnciicallc. The indigo is ottifned froin satine chloride, whiehin turn is made froin benzol. Natural caverus of lar e size, ono at least pcinu' six hundrcd feet long, have len discovcred at West Harp tree, iar Wells, Soinci'getsbire, England. It is hinlccl that the inveskiuations bive revealed matten of i''eat iiilcrdt to antiquaries aud afchsealotfiBta. J. Mace and "W. Kicati, in a paper on lm disLiibution of llght iii the speet ïnni, say that they consider two quniiiitifs of light as respectlvely equiil viiinn they, illiiiniimtinii Olie Buil the saine oolorlesa object, piacoa at the same distance iroin tlie observer, euable hiin to see its details with tlie same distinction. Whilc the uendulom is considerably affected by the near presenoe of lc ii-.,. mekr hills, and bv ll"'t of such sinall .■irti'n:..' m:isses aa the great pyr.iinid ot Gizeh, hugc mountains liko the Ilinialayas ami great eicvated plateaus aud table-lands do not inlltKMice thu peudulum indicationa in jui appreciable degree. M. Faye offers lor these and other HUe facts the broad sohuion : Under the oocani liii; globe coois more rapully and to ii greater neptli than bime.uti the siii'iiii'o of tlie uuiitincnts. At the depth oí' 4,000 metras the oceau will stiil have a temperatura not, far from o dogrees Centigraae, vrhile at a similar iieptbi uciicuüi tiie earth's crust the tejnperaiure would not be luifrom löO iiei'oos. It' tlie earth had but onc uniform vate ot' cooling all over it, it would be rcasoiiable to assuine tliat tho solidiüea ernst would have tlie same tliiekuess and the same average density ali over it. Below the primitive oceaii8, therefore, Lhe eartii's crost assumeJ a defluite solid tliiekuess bcfore the coiitiiienLs, and, ÍM conlractiug, these thicker portions exeroised a pressure upon the fluid nueleus tending to elévate the conti. nts still higher. Ia this way the uiiequal distribución of land aud sea at tiie poles is aiso explained. In a note to the Paris Acadeinj',Prof. Marangoni gives the resulta lio basar. l'ived at in a stuay oí" the swiinniingbladder. He staies, first, tliat tt ís the orgaii whioli regúlate tila migration ot íishes, those iishos tlwt are made without it not migratiiig froin tlie liltle dtípth, whero they íini tepiá water; while iishes whioh liave a bladder are sucli as live ia deep, cold water, ;uid nngrate lo depoatt their ova in wanner water lioar me surfaee. Huxt, lislius do not rise liue tlie Cartei.in üiver (in tlie well-known exjernueut), and they liave to eouiiteract Ihe iiiíluenee oí' their swiiinnnigjladaer with their ñná. It' some mail dead and living lislies be put in a vessel threo-quurters mil of water Uil tlie air be compiessed or raro lie i, one linas in tlie íbnner case tlie uead Lsu uesceiid wliile the living ones -.-e, Uu,,., ;., lutvanr.i', ■' "" ''■ ' ■■ Uveiying rare opposile ettect.. - riSlies have reasun to lear tiie passive nüuences nue to nydrostatic pressure ; vhen flshed Irorn a yreat deptn, tlieir )ludaur sceius to be rupLiiretl. Xhirdy, the swiinuiiujj-bladuer produces n liohes twotoid instubility - one of cvei, llie other of position. A lish, lavmg ouce adapled lts blaader to ive at a certuin uepth, ma. , through he slihwst varialion oí' pressure, be ither forced downward or upward, ml tnus they are in unsiable equiibriuui as to level. As to uosiuon, he bladder beiug in the ventral reiun, the centre of gravity is above he centre ot' prussure, so tliat the ishus are always tliruatenod with in'ursion ; aiKt, iuueed, they tatce tne nverted position whenuead ordying. .'nis uouule insubility loices nalioa o a oununual y innastic ïuovenient, Uil douutiL'Sri lielps to ren. .er Lhelu irong and ayilf. l'ne most agjle of errestrial anunals are also those vhich have least stabiiity.