SCIENTIFIC AND USEFUL.

Lake Wakatip Mail, Issue 1860, 26 February 1892, Page 3

SCIENTIFIC AND USEFUL.

INTFRACTION OP THE OPTIC HBBVKS. When we observe a white surface with one eye for a short time through a bit of coloured glass after the glass is removed the white surface appears to be tinted with the complementary colour of the glass. That is a comparatively well-known fret; but M. Chauveau points 01.t that if the eye first used is closed, and the white surface is examined with the other, it appears to be of the same colour as lh« glas j . That would appear to show that the optic nerves of the closed eye are acted upon by those of the examining eye. ARTIFICIAL OLASB. A substitute for glas* has been invented by Fried rich Eckstein, of Vienna, It is composed of collodion wool, ether or alcohol, castor oil, and CanaJa balsam. The compound, when poured out on a level plate, and dried by a current of warm air, solidifies into a sheet of material possessing all the properties of glass, such as perfect transparency. It d'ffers, however, from ordinary plate-gla.'s in bring flexible, which enabli s it to be used in many ways where glars would be inapplicable. By the admixture of proper pigments, any d sired colour can be imparted to the compound. GOITHB AND CRETINISM. It appears that goitre is increaiing in France, no fewer than 420 000 persons being affected in 30 of the departments. It. i* technically a swelling of the thyiod gland and is known here generally as Derbyshire neck. It is often found ac-ompnnied by cretinism, which, it feetns, is becom ng more citnm'm in iho valleys of the Alps and the Pyrenees The origin of the term does n't seem to be known; but it means imperfect developm-nt, not to say deformity, of the whole bo ly, and is found chiefly amongst those who live in the valleys of mountainous distric's. The Frenc'i Government will probably be asked to order an inquiry inlo the whole subject. THE DiNANA. The binana belongs to the lily family, and is a developo I tropical lilj, from which, by ages of cultivation, the reeds have been eliminated and tho fruit, for which it was cultivated, grest'y expandel. In relation to tho bearing qial tifs of this fruit, Humboldt, who early saw the wonders of the plant, siid that the ground that would grow 90 pounds of pota'o'j would a'so grow 33 pounds of wheat, but that (ho same ground would grow 4000 pounds of the proportions thus to wheit, 133 to 1, and to pota'oes, 44 to 1. The banana posj 'sses all of the essentials to the sust nance of lif-*. The savage of the sea is'es and tho jungle o*es what ho has of physical sbengt itoth s food. Wheat alone, potatoes al >ne, will not do thi». THE XtOOO LEGACY. The Institute of France has accepted the of JMOOO, the of which is to bo given in prizes to the scientist who m iy suggest the best m-'iin* for iievi«ing m-ana of CJin t unication with signils between thisworl 1 and the other planets. M. Amalie Guillaumin does no? see how the money to bequ-athud can be spent. The moon, the nearest celestial body to us, is so far off th >t no p > sible signal could bo seen there, supposing it. inhabited, an i llais ii 50 tiinei more distant. Ho believes that the interest of the .£4OOO must go on increasing for an en ile«s number of years, and thea when the snowball has become an avalanche, some future Legislature will make a law to app-opriita the vast sum so accumulated to a practical purpose. S\OACITr OP A WILD DUCK. Mr VV. Prentig, of Rainham, Kent, describes in the October number of the Zoologitt an interesting cise of a wild duck's forethought. A mowing-machine was set to work round the out'i 'e of a field of lucerne borderiug a marsh, diminishing the circle each time round the field, leaving about two acre? in the centre. A wild duck was seen Ky the shepherd to fly from the pie?* of lucerne that was left with something in her beak, and, happening to fly near him, sh * dropp -d^three p irts incubated egg. She w,ts agiin observed by the shepherd, and als > by the s!ie<?p--he i-er, carrying another eg in her beak, this time ovor the marsh-wall towards the saltings ; and again «he was seen for the third time carrying an egg in her bejk in the same direction. Next day, when the field was " finished " by the removal of the la«t piece of lucerne, the wild duck's nest from which tho same had b-'en removed was discovered.

THE ST. CLAIR TUNNEL. The St. Chir Tunnel, an international work, which fornix a Nn 1 connection between the Canadian lines and the American lines running to Chicigo, which has a length of 6,026 f*et, or 11,553 ft. including itseiciva'ed approaches, i< constructed under the bed of the St. Clair River, between Point Elward, in Ontario, and Port Huron, in the State of Michigan. It is 20 in diameter, and is lined throughout with ca*t-iron platrs 2'\n/\n thickness, the lining weighing altogether 28,000 tons. Hitherto the trains have been carried across the S'. Clair River on hui?e ferry boats, which were liable to be delayed by ice in the winter, in a Idition to the ever-present risk of crossing a rapid stream. The tunnel not only abolishes these danger?, but reduces the length of the journey by six miles. Arrangements have been nude for electric lighting all through the tunnel, and for thorough ventilation. LIGHTHOUSE ILLUMINANT3 Mr John R. Wighim, of Dublin, points out the disadvantages of the electric light for lighthouse purpose. In clear weather it is dnzzling and misleading to the mariner, and in foggy weather it is compnratively useless. This evidence is strikingly corroborated by the recent manifesto of the London Shipmasters' Society, who state that in certain conditions of the atmosphere the electric light is invisible, while oil lights of lightships, and gas lights of seaside-towns, are comparatively bright and distinct; an 1 still moro recently confirmed by the French lighthouse authorities respecting the lighthouses of Capo La Ilevre, where, for a time, an oil-light was substituted for one of the electric light', when it was found that in very thick weather, though it was impossible to make out the electria iight, the oil-light was still sufficiently visible. HOW TELhGRAPH WIRES CAME TO DE LAID UNDEBOROUND IN CHINA. When the first Chinese telegraph company went co work to put up the poles on which to hang its wir-s, the workmen were embarrassed every little while by wrathful Chinamen, who would rush angrily upon certain po'es and chop th"m to the ground, and warn the workmen with much furious chatter that they would put them up again at their peril. The cau*e o' this interference was unknown to the workmen, who were at last forced to disc>ntinue the work, and an explanation was demanded by the authoritio?. Then it was learned that the poles that were cut down had cast a shadow sometime during the day on the grates of revered ancestors of Chinamen, and the insult could bo wiped out in no other way but by summarily removing the poles. It was found that this superstition was too sicred a one among the Chinese to be overcome by parsuasion or bribery, and ut la»t the telegraph company, as a matier of economy and selfprotection, laid their wires beneath the surface, where they have bpen cvor since.