SCIENCE NOTES.

New Zealand Mail, Issue 1514, 7 March 1901, Page 61

SCIENCE NOTES.

THEY SING WITH THEIR WINGS. The humming noise produced' by the bees and flies may be expressed in' a musical notation. Thus the common house fly often produces the sound F. In order to do this the creature must vibrate its wings 21,120 times a minute, or 335 times a second. The honey bee frequently produces the sound A, and vibrates its wings 20,400 times a minute, or 440 times a. second. In this way one can ascertain the number of vibrations the little creatures are producing with their wings by finding out what note they are humming. THE PHOTOGRAPHIC!STAR MAP. The new star map or globe, which is being constructed under the auspices of the International Congress of Astronomers is: an amazing work. Photographs are being taken of given sections of the sky from stations all over the world, these to be arranged into a complete map of the heavens. The patchwork of photographs will cover an immense globe having a diameter of 24ft. During, the work 44,000 photographs will be taken, and a catalogue of 2,500,00.0 stars will be made. Altogether more than 30,000,000 stars will be photographed. The lens of the camera is of more astronomical value than that of the finest telescope. More accuracy obtains in measuring a plate than was possible in visual measurement. One five hundred thousandth of an inch and less on a photographic plate furnishes data for accurate star measurement; where the telescope will show but 50,000,000 stars, the sensitised plate exhibits more than 160,000,000. Though light travels at the inconceivable velocity of 187,000 miles a second, yet light from some stars in the range of the telescope takes 5760 years to reach the earth. We may see on the photographic plate pictures of stars, not as they are, but as they were perhaps half a million years ago. IS LIFE BECOMING LESS WORTH HAVING ? In Fratiee the number of suicides has increased in fifty years by more than 200 per cent., while the population ha® only increased by 18 per cent. In Belgium and a large part of Germany the rate of suicide has about doubled in the same period). In Denmark the rate has practically stood still. In England and Wales it has increased from 68 per million in the first twenty years of the Queen’s reign to 86.5 in the five years preceding her diamond jubilee. It would be interesting to know whether this increase is due to general degeneracy or to the greater strain of living in these latter years. In this respect comparative statistics from town and country should be of value. LIQUID AIR. For obtaining an exact idea as to liquid air there is a very simple method, in the opinion of M. Robert Fitavel, who makes this observation in “L’Aluminium,” and that is to consider it as the extreme limit of compressed air, when one can easily conceive' that it may be employed as a refrigerating agent, as motive power, and as explosive force. Again, its composition sufficiently indicates , that it may be a source of c-xygen. which., as is well known, has many uses; but the success of all these applications depends upon a principal factor, which is the sale price l , and consequently the cost price l , of liquid air. This substance may, in fact, serve to afford liquid oxygen, owing to the differences of volatility in the two elements which compose it. By evaporating one half a given mass of liquid air a concentration of oxygen to 85 per cent, is obtained, and, on pushing the evaporation further, nearly all the nitrogen, may be eliminated. The author firmly believes in the future of liquid air, which, has hitherto been experimented with in apparatus not intended for it, but when the appliances are perfected, and the cost of production diminished it will certainly be demanded for purposes hitherto unsuspected. MORE “AIRSHIPS. The American papers speak of a “Custard Airship Company,” which has a factory at Elmott, Texas, for the manufacture of airships on an “original plan.’’ This company was organised several months ago, and endeavoured to manufacture machines in time to establish a line of them to ply between New York and Paris during the course of the Exhibition at the French capital but their construction was delayed, and it will be several months, so we are told, before regular line® of airships will be established between principal cities, should the one that is to be launched prove the success that is anticipated. The complete machine weighs 250 pounds, and it has a carrying capacity of from three to five people. Its maximum speed is expected to be 100 mile® per hour. THE! VELOCITY OF LIGHT. The velocity of light has recently been determined by M. Perrotin, who gave some particulars of the experiments at a meeting of the Paris Academy of Fizeau’s method was adopted, the distance between the two stations Being nearly 12 kiloms. The mean result of 1500 observations was 299,900 i kiloms per second.