Science Sittings

New Zealand Tablet, Volume XXXVI, Issue 1, 2 January 1908, Page 35

Science Sittings

By •Volt'

The Deepest Lake. Lake Baikal, i'h Siberia, is by far the deepest lake known in the world. It is in every way comparable to the Great Lakes as regards size, iqr, while its area is , more than nine thousand square miles, making it about equal to Erie- in superficial area, its enormous .depth of between 4000 and 4500 feet makes the volume of its waters almost equal to that of Lake Superior. Although its surface is 1350 feet above sea level, its bottom is nearly' 3000 feet below it. 'Fortunes in Broken Glass. The waste from glass furnaces is now made useful. Into a fire-resSsting mould are placed fragments of glass of various colors, which are then raised to a high tempetature. The coherent mass thus produced can be dressed and cut into beautiful mottled blocks and slabs, forming an artificial marble of decorative surface. Designs in relief can be obtained by pressure while the material is slill plastic. From broken glass a ' stained glass ' window can be made by firing without the ordinary slow process of ' leading.' A prosaic soda-water bottle in the final fulfilment of its destiny may dazzle the eyes as brilliant ' diamonds ' or other 'precious stones.' Thus does the 'waste', come to resemble the most precious commodity if properly handled '-and utilised. Heat and Light. The rays of heat and light are quite independent of each other in their ability to penetrate different substances. For illustration, glass allows the sun's heat to pass through as readily. as it does the rays of light, and that without heating the glass too. If the_ glass be coated with lampblack, however, the- rays of light are arrested, but the heat passes through as before, not a single degree's difference in the latter phenomenon being noticeable. Then, again, both heat and light pass through s water, provided it is clear. One of the oddities in this connection is this : Al1 hough the heat and light pass through the water in its normal state, the addition of a little powdered alum, which readily dissolves without leaving the leasti murkiness, will arrest the rays of heat to such an extent as to almost immediately raise the temperature , of the water to a perceptible degree, yet the light continues lo pass through as before. Ice, like glass, also transmits both heat and light. 'Several pieces of granite were once found deeply embedded in N ice without any communications with outside air. These were all surrounded with what might be termed an atmosphere of water. The explanation of such an oddity is this : The heat passing through the ice had been absorbed by the stones until their tem>peratu<refhad. been raised to a degree sufficient to melt the ice around them. Disappearing Islands. Submarine volcanoes are' the cause of many deepsea phenomena. Among the most curious of these are islands that come and stay awhile, then vanish in a night as completely as though the earth had swallowed them — or the sea, which is really the v hungry maw which opens up to gorge itself upon these lost Atlan- - tises. In 1831 an island which received the baptismal name 1 of Julia appeared off the south coast' of Sicily. 'After an earthly existence of just two months it was ■ again received into the deep, which had given and then taken away. Soundings which were taken at' the spot showed a depth of fifty metres. An island called Sabrina appeared in 18.11 near the Azores and disappeared the same year. Here the depth sounded afterward was very -great, an enormous fissure being traceable having a depth of at least thirty-five hundred metres. These eruptions generally occur in shallow water. The Island Georgios, in the Archipelago of Santorin,' is a comparative infant in land" annals, having made its appearance so late as 1866. " About six years ago, in September, 1901, tiny island of Bermuja, in the southern waters' of -the Gulf of Mexico suddenly disappeared. A well-known French hydrographer, M. Thonlet, says there are two great zones of volcanic activity — the terrestrial one running through Central America, Mexico, the Antilles, the south of Spain, Santorin,?*the Red Sea, and the Persian Gulf to the Malay Archipelago, „ while the . marine volcanic *one traverses the -^Atlantic, near Tristan d'Acunha, St. Helena, Ascension, the Canaries, the Azores, and Madeira.