SCIENCE SIFTINGS

New Zealand Tablet, Volume L, Issue 14, 12 April 1923, Page 54

SCIENCE SIFTINGS

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How Far Can You See? Do you know that your eyesight is affected by the place in which you live? To have really good sight you must reside in a country where the land is flat and unbroken. The people with the best sight are found in the neighborhood of the North Pole and at the Equator. In the first of these places there are frozen wastes; in the other there are vast deserts. An Eskimo can see a white fox against the snow at an incredible distance, and an Arab can name objects at a distance of five miles. . In America those who live on the great plains have wonderful sight, since the country is without obstacles which shorten the range of vision. In Europe the Norwegians are gifted with the best eyesight. Those who live in towns and cities have the worst sight. The Advantage of Being Big. As a rule, large animals live longest. The life of an elephant is 14 times that of a rabbit, while that of a goose is eight to ten times that of a sparrow. The whale is perhaps the longest lived of all warm-blooded creatures. To some extent this rule applies also to the human race. The big races include English, Scotch, Scandinavians, Bulgarians, and the Northern or Tartar Chinese. The average weight of an adult man of these races is about 150 pounds. Next come French, Italians, Spaniards, Arabs, Turks, and Southern Chinese. Their average weight is between 135 and 140 pounds. The small races are Eskimo, Mongol, Burmese, Japanese, Bengalese, Malays, Javanese, and Hottentots, whose average weight when full grown is between 120 and 130 pounds. An Eskimo is very old at forty, and few Malays live beyond fifty-five. English and Scottish men live on an average ten years longer than Italians or Turks. Climate and food modify length of life in various' parts of the world, but the averages mentioned hold good. How the Size of Stars is Measured. The last of the six steps by which astronomy has advanced in a century was described to the children at the Royal Institution, London, recently. It was the measuring of the size of a star. Professor H. H. Turner said that it was far easier to measure the weight of a star than its size; in fact, the weight of the stars did not vary greatly, the small ones being about one-fifth of that of the sun and the heavy ones being about five suns' weight. The difficulty in measuring the size of a star was that even the largest telescope did not show any star as more than a point of light, something quite immeasurable. If, however, the photograph of one of these points of light was examined microscopically it was found to be made up of dark and light rings caused by the phenomenon known as "interference." When it was first proposed to calculate the size of the red star in the shoulder of Oroin, Professor Eddington considered that it would need a telescope with a mirror Bft or more across to produce measurable interference rings, but Michelson, an American, designed an instrument called an interferometer, in which a small telescope took simultaneous observations from two different points, in the same way as a range-finder. In this way they got measurable interference bands and proved that the star, although little heavier than the sun, had over 400 times its diameter. Since then many stars have been measured. — Manchester Guardian..