Scientific and Useful.

Lake Wakatip Mail, Issue 1588, 6 May 1887, Page 3

Scientific and Useful.

CAUSE OP EVOLUTION. The more deeply nature is studied, the more certain seems to be the conclusion that all her variety is tbe result of evolution. It seems alfo to be more and more certain (hat natural selection is not the cause of evolution, but only its guide. Veriation is tbe cats eof evolution, but the cause of variation is unknown. It seems to be a mistake to call variation spontaneous, fortuitous, or accidental, than with expresiions no adjective less accurate or more misleading could be found. The Athenian philosophers displayed a )'ess unscientific altitude of mind towards th e unknown when they bui't an altar in its honour. —H. Sebohn. MKTEOROLOG r. The prognostication of storms and meteorology are becoming more exact sciences as the laws affecting storms become understood. Mr Eddy, of the American Signal Service Buroau, stntes that of 38 predictions of tornadoes in April and June, ISBS, 18 were verified. Those of 1886 were, however, far more exact, a? out of 19 prophecies 15 were absolutely fu'filled, and the indications in the remaining j leur showed that wind and hailstorms prevailed. Signor Ferari, of Italy, after studying the ciuse and the effects of 6.~>0 storms, has come to the conclusion that every thunderstorm is connected with a barometric, hydrogenic, and thermic depression, being behind the two former but in front of the last. — Mechanical World. MIRAGE PHENOMENON. A correspondent writes from Venice to the Frankfurter that one °r two days before Christmas a singu'ar phenomenon was seen at Saviile, near Cdine, which recalls accounts of the mirage sometimes presented near MesFino. The sky was partially covered by clouds, in which the surface of a ca'm sea was discerned, with boats passing, over it, and even a steamer cutt ;its way Presently houas come in view, then large, beautiful buildings, palaces, and churches, and, as the fea'. ures became more defined, the cathedral of St Mark, with the Piazza, and tower, were plainly presented, and the neighbouring canal?. The spectacle faded gradually away, having made a great impression on all who saw it. EFFECT OK ELECTRIC LIGHT ON FLANT GROWTH. It is some years ago since the late Sir Wm. Siemens demonstrated frcm experiments carried out in his own greenhouse that the employment of the electric light at night had an iii'portunt influence on the growth of plants. The following instance which occurred lately at Davenport, Pa., U.S.A., gives an accidental confirmation of the above experiments. A system of electric lighting was introduced into the city of Davenport last spring, and near the reesidence of a Mr llenry Kerker was situated one of tho electric fight towers. This tower is 135 ft. high and contains fivo arc lights, each of 2000 car.dlepower. During the past summer Mr Kerker's attention was attracted to the singular effect these lights produced upon some day lilies blooming in his garden. These flowers closed as night came on, but as soon as the electric lamps were started up they reopened, and while the lights were in operation continued in full bloom. As the street is about SOft. wide\ the lights were distant tome 200 ft. from the flowers. EGG FXH.OSION. The explosion of an ostrich egg in tho hands of a scientific man is not a common occurrence, and the recent accident at Vale College lias eic.ted considerable comment. Mr Bauer, at the Pcabody Museum, New Haven, Ccnn., was boring a hole in an African egg, weighing about three pounds, when it exploded and knocked him senseless, irjuring him severely, and wounding some of the bystanders. Such explosions on a small scale are a common incident on the Chinese coast. A common fashion of preserving hens' egts for sea use is to pack them in lime, Jand if properly ptcked they will keep sweet for some months; but they are not always thus picked. Sometimes a vessel leaves a Chineso port with a large supply of eggs, warranted to keep all the voyage home ; but in a week or two they begin to go bad in a most extraordinary manner. The lime has such an effect on them that it generates a peculiai foul-smelJing gas, and tie moment the shell receives a crack it j eiplodes. At first the eiplosions are rare | and very mild ; but in a few week" the " preI served" go off with a report like a pistol, vith an cver-incrcaaing odour ard (frequency, and are finally relegated to the sailors, who find considerable amusement with them. The explosion at Vale, which las ended so disastrously to Mr Bauer, is doubtless due to the same cause ; but the strong shell of the ostrich egg has tt stifled the evil result. — Liverpool Mercury. DISSECTING AN ELEPHANT. The New York World suys that, in the presence of a dozen students, Dr R.S. Iluidekoper, dean of the veterinary department of the University Pennsylvania, on the 12th ult. dissected the body of the thirteen-year-old elephant Dom Pedro, who ditd at the Zoological Garden from inflammatory rheumatism. When last measured hcwas7fe»et P> ircheshigh, ar.d weighed about -MX) lbs. Tho lungs and heart were so large |i» |to require two men to lift them. The skeleton will be set up in the museum, and minute study will be given to every portion of the anatomy of the beast. Doin Pedro wag cno of the most vicious animals ever in the Zoo. For the last four years he has been kept in close confinement because of his dangerous character. Twice he attempted to kill his keeper, and once would have succeedid but for the interference of Another elephant. As it was, the Bian escaped with a broken collar bone, and j ha'f a dozen broken ribs. Dom Pedro was taken with rheumatism early in June, and I grew weaker u» til he died. For the last week he wfs unable to stand up, but his vindictive temper lemaired unbroken to the very li st. His rame aro<e from the fact that the di y of 1 is arrival at t lie Zoo from New York, bling lien three years old, Dom Pedro, imieor of Brazil, was doing fhe Zoo. The woikmin immediately transferred his name to (he baby elephant. NIW rsE FOR THE RADIOMETER. M. lirere, manager of the !St Qutntin Gasworks, Froi ce, has brought forwi rd a projositienof employing the radiometer in gasv orks to indicate the titre fcr putting on the mght pressure. lie »ays he has himstlf used the ii st.-ument in this way for son e months, and has f« urd it set satisfactorily. It is constructed in the ueual way—viz., a glass globe in which four vines, black on one side and white on the other, revolved almost in vacuo j the motive power being furnished by tbe increased pressure impaitedtotheairon coming in contact with tbe hot'eft part of the apparatus —that is to say, the blackened sides of the vanes. It is well known that as long as there is snfficient light the vanes will turn; but when th« luminous rays become feeble, tie rotary movement ceaacs. If t}ie radiometer is exposed to the setting sun, tho varies stop, in very clear weather, about 20 minutes after sunset ; and in very dull weather sometimes 30 minutes before sunset. In applying Mr Frere recommends that the workman in charge of tbe governors should begin to put on the pressure five minutes after the stoppage of the vanes; and if this were done, the consumers would, he suvs, have a proper supply of gas at the moment they require it,