Science Siftings

New Zealand Tablet, Volume LII, Issue 9, 11 March 1925, Page 62

Science Siftings

By “Volt"

The Deepest Sea, -The discovery of a spot in the Pacific Ocean, south-west of Japan, 32,636 feet deep, will not greatly astonish oceanographers, for the Pacific has long been known as the deepest of all the great seas of the globe. Nowhere else has any depth been reached as great as 30,000 feet, but in the Pacific as many as ten soundings have been made exceeding that figure. In the Atlantic only two places are known with depths greater than 24,000 feet, the deepest being a spot north of the West Indies, where the lead found bottom at 27,972 feet. “Pullmans” of the Air, Not more than a dozen years ago an aeroplane was a curiosity, and people would go miles to see one. It is a far cry from the crude models of those days to the Rolls-Royce W 8 air expresses which are now operating on the Imperial Airways winter service between London and Paris. Behind the pilot is a long, low saloon, which has been fitted to be in every way a counterpart of the most luxurious Pullman carriage on the railways. Ample room is provided for the accommodation of fourteen passengers, and for each there is a comfortable, cushioned armchair. Mahogany fittings, flower vases, mirrors, shaded electric lights and draughtproof windows all add to the comfort of passengers, while an improved system of heating keeps them warm. There is also a carpeted passageway up the centre of the saloon, and shelves, containing books and periodicals, are within easy reach. Those who make many journeys to the Continent by air read just as much as passengers who travel by sea or land. The novelty of flying does not last very long. Weather Wisdom. “Red at night is the shepherd’s delight, Red in the morning is the shepherd’s warning.” This is the old English rhyme, but the idea it expresses is known in nearly every country in the world. Even the ancient Egyptians and Greeks had sayings similar to the above. Furthermore, it is scientifically true. Red skies are really weather forecasts. If the atmosphere is clear in the evening or morning the sun’s light is red, because the blue, of which the ordinary white light of the sun is made up, has been absorbed by the great length of atmosphere through which the slanting rays of the sun have to pass. In the evening the rosy light of the sunset illumines the clouds on the eastern side of the sky. This shows that the clouds have gone by and are taking the rain with them. Thus we get red at night, indicating fine weather. In the morning, the rising sun being in the east, the light illuminates the western horizon and its clouds, which are on their ■way to us. We need not be shepherds to know that if the sky is red and dowering

in the morning we are in for a good “soaker” before lunch-time comes. A Wood Lighter than Cork. “What is the lightest wood in the world?” asked Edison in his famous questionnaire, and few were able to answer off-hand. The distinction of superlative lightness belongs to a tropical American tree known as the balsa. Its wood is lighter even than cork, which is only a bark. “Balsa” is the Spanish word for raft, and the tree was so named because the Spaniards who conquered Central America found the Indians using its rough-hewn trunks for rafts. According to the botanists, the balsa tree is akin to the mallows, the hollyhocks and cotton. Balsa is rapidly finding many commercial uses. During the World War thousands of mines in the North Sea were attached to balsa floats. Its extreme porousness makes it a most efficient non-conductor of heat, and so it is being employed in the manufacture of refrigerator plants. It is competing with cork in many of the latter’s functions. As in its normal condition the wood decays rapidly, for commercial employment it has been found necessary to treat it chemically to preserve it. “It is interesting to note,” writes R. N. Davis, curator of Everhart Museum, :n Nature Magazine, ‘that in the tropics there are great extremes in the density of woods. While we have no wood that will sink in - water when seasoned, many of the woods of-'r" the tropics have a greater specific gravity than water when green. Among them are the quebracho, ebony, and lignum vitae. In our temperate latitudes the trees do not go to such extremes. Our lightest wood is considered the arbor vitae, with a weight of twenty pounds to the cubic foot, while our heaviest is hickory, which weighs fifty-two. (Water weighs 62.5 pounds per cubic foot). Some specimens of the balsa weigh only. seven pounds to the cubic foot, whilst some of the heavy woods run into the eighties. While there are extensive forests yet in the tropics, the trees are either extremely light and soft or else are very heavy and hard to handle. The tropical forests are made up of numerous species mixed together, and few of the trees are adapted to general purposes like our conifers and hardwoods.”