The Arkansaw traveler., 1886-05-22
CompRod tor The Arhaasav TsuveseY SCIENTIFIC MISCELLANY

It appears that many fruits acquire most of their growth by night The fruit of the cherry laurel, for instance, has been found by Dr. Krauss, of Halle, to increase at the rate of ninety per cent. at night, and only ten per cent by day while apples increase eighty per cent at night, and twenty per cent in the daytime
 The botanic gardens of the world, most of them scientific in character, are reported to number l97, of which Ger many has 34; Italy, 3; France, 20; Great Britain and Ireland, l2; West Indies, 6; and the United States, ,; More than half are supported by gov ernment, and only five per cent. by pri- vate enterprise.
 An Italian physicist, Signor Bombicci, l seeks to account for the fact that meteor. ties are largely composed of iron by supposing the earth's magnetism to be the influence which chiefly attracts the floating fragments of space. This view is supported by the large finds of me teoric iron near the accessible pole of our planetary magnet
 A New Plaster.-A new plaster or artificial fre-proof stone has for its chief constituent the mineral asbestine a silieate of magnesium To this is added powdered flint and caustic pot ash, with sufficient water-glass (silicate of soda) to make it into an adhesive plaster. Sand also is mixed with it be- fore use. No lathisg is necessary as the mixture adheres to any smooth wood ] or metallic surface.
 Tea Poisoning ng-Chronic tea poison ing, according to Dr. w. \. Bullard is frequent affection, the most common symptoms of which are loss of appetite, dyspepsia, palpitation, headache, vom- itlng and nausea, combined with ner- vousness, and hysterical and neuralgia affections, frequently accompanied by constipation and pain about the heart Among adult women the average amount needed to cause poisonous symptoms is little less than five cups daily but the young and weak are more easily affected.
 Mystery Explained -Profs. Ayrton and Perry, the English electricians, have accidentally observed that on amalgamation, or coating with quick silver, brass expands, SO that if one side only is amalgamated plate of brass becomes curved. They imagine that this may be the primary cause of the phenomena of the Japanese magic mirror which has cast on the back a pattern that is quite invisible on the polished face yet is mysteriously dis tinct in the patch of light reflected by the mirror upon a screen. Amalgama- tion would effect the thinner parts made by the pattern more than the rest of the plate, giving the mirror the impercepti- ble unevenness that becomes plainly apparent in the reflected image,
  uralist remarks that it is a sad reflection that while the turbot lays 14000,000 eggs, not more than one, on an average, ever lives to reach maturity In fish generally it takes yearly at least hun dred thousand eggs for each individual to keep up the average of the species. In frogs and amphibians few hundred are amply sufficient Reptiles often lay only much smaller number In birds, which hatch their own eggs and feed their young, from ten to two eggs per annum are quite sufficient to replenish the earth Among mammals, three or four at a birth is a rare number and many of the larger sorts produce one calf or foal at time only. In the hu- man race at large total of five or six children for each married couple during a whole lifetime makes up sufficiently for infant mortality and all other sources of loss though among savages far higher rate is usually necessary. In England an average of four and a half children per family suffices to keep the population stationary.
 The Flow of Metals-In one of his recent interesting lectures in London, Prof. Roberts-Austen spoke of eight prominent points of resemblance be- tween metals and fluids which have long been known They are the reiec- tion of impurities on qualification, suffu- sion, flow under pressure, changes due to compression, absorption of gases, absorp- tion of liquids, vaporization, and surface tension. Of these properties perhaps the most astonishing are those exhibited