SCIENTIFIC.

Otago Witness, Issue 1916, 10 August 1888, Page 35

SCIENTIFIC.

— The distinguished German botanist, Professor Sachs, has discovered that the ultra violet and invisible rays of the solar spectrum are especially efficacious in the development of flowers. If these rays are suppressed, the vegetative organs grow luxuriously, but the flowers are almost entirely suppressed. The professor thinks that extremely small quantities of one or more substances, formed in the "leaves cause the formative materials -which are conveyed to the growing points to take the^form of flowers. They act 1 like ferments, sd-that extremely small quantities of the flower substances act upon large quantities of plastic substances. ,

' — Mr R. A. Proctor says that so far as telescopes and physical researches have yefc led us,in size, in situation and. in .density, in the length of her seasons and of -her rotation, in "'the- figure of her orbit and s in the ■ amount of light and- heat she receives from the sun* 1 Venus bears a more striking resemblance to" the earth than any^rb within., the solar system. -In faot>, there is no other.!, pair -of planets between which $o many analogies can be traced as between Venus and the earth, Uranus and Neptune aresimilar in many respects, but they differ in v at least as many. Jupiter and Saturn are, in a sense, the brother giants of the solar scheme, while the dwarf orbs, Mars and Mercury, present many striking points of simi- \ larity, but between hone ot these pairs can we trace so many features of resemblance as ■ those which characterise the twin planets., 1 Venus and Terra, while the features of dissimilarity in either pair are perhaps even more obvious than tha points of resemblance.Had Venus but a moon like the earth, we might doubt whether, in the whole universe, two orbs exist which are so strikingly simi- ' lar to each other. Indeed, it is by no means certain that Venus has not a moon ; Montaigne, Rodkier, Horrebon, Monthaven, and others having seen a body near Venus, which presented a phase similar to that of the planet, precisely as a satellite wouldhave done. Venus has a day of about 23hr ' 21min, and a year of 224 days 17hr nearly. ' The distance from the sun is something less than three-fourths of that which separates ( the sun from us. It is clear that merely in the greater proximity of Venus to> the sun, there is little to render at least a large proportion of her surface uninhabitable by such • beings* as exist on our earth. In her ter- \ perate and sub-Arctic regions, a climate which we should find well suited to our requirements, might very well exist ; while the Polar regions t might correspond to our ■ temperate zones, and be the abode of the most active and enterpiising race existing upon her surface. On the whole the cvi- , dence we bave points very strongly to Venus ' as the abode of living creatures not unlike the inhabitants of the earth.

— The principal element in the composition of a tear is, sls may readily be supposed, water. The other elements are salt, ' soda, phosphate of lime, phosphate of soda, ' and mucus, each in small proportions. A dried tear seen through a microscope of' good average power presents a peculiar appearance. The water, after evaporation, leaves behind it the saline ingredients, which amalgamate and form themselves into lengthened cross lines, and look like a number of minute fish bones. The tears are secreted in what are called the "lachrymal glands," situated over the eyeball and underneath the lid. The contents of these glands are carried along and under the inner surface of the eyelids by means of six or seven very fine channels, and are discharged a little above the cartilage supporting the lid. The discharge of tears from the lachrymal glands is not occasional and accidental, as is commonly supposed, but continuous. It goes on both day and night — though less abundantly at night — through the "conduits," and spreads equally over the surface of the pupil in virtue of the incessant movement of the lids. After serving its purpose, the flow is carried away by two little drains, situated in that corner of each eye nearest the nose — into which they run — and called the "lachyrmal points." The usefulness of this quiet flow of tears, to both men and beasts, is manifest. There is such an, immense quantity of fine dust floating in the air, and constantly getting into the eyes, that, but for it, they would soon become choked. Very little is requisite to keep the ball free, and when some obnoxious substance—smoke, an insect, or the like that affects the nerves — does make its way in, an increased flow is poured out to sweep it away.

— The old plan of using an endless railway to embrace the wheels of vehicles which have to traverse soft soil or ' swampy situations has lately been revived by Mr William Fender, of Buenos Ayres. The method, as before tried, did not prove satisfactory ; but Mr Fender has made several improvements in the system, by which difficulties have been made to disappear. The railway consists of a chain of flat slabs of hardwood, which are rivetted between thin steel plates, and are linked together. The chain embraces the wheels, so that, as they turn, the blocks form themselves into a railway in front of •them. The system has been used with great success in carting beetroot Over , swampy grounds in the neighourhood of Berlin ; and it is thought that it may be profitably employed in ordinary ploughing operations with a single engine, superseding the double system which is now common in this country. ,

Mr W. C. Robert-Austen, the chemist to fche London Mint, lias conducted an elaborate .series of experiments on the effect of small quantities of impurities on the properties of metals. It is well-known how mimite are the quantities ( of carbon necessary to convert wrought iron into steel or cast iron. Nowadays, by taking some simple precautions to exclude certain impurities from copper, cables can be got fco carry twice as many messages as the cables of 30 years ago. Gold shows itself to be very susceptible fro fche ininT'iice of small quantities of impurity. One part oE bi«muth to 2000 of gold renders the latter quite brittle. This subject is connected with that of the properties of alloys which are being produced in great variety and with an equal variety of valuable properties. {Continued on page S7.J - '