Science Siftings

New Zealand Tablet, Volume LII, Issue 5, 4 February 1925, Page 62

Science Siftings

By “Volt”

The Handiest Number. There is a peculiarity in connection with the figure 9 which is frequently turned to account in banks, where nine is consequently regarded as the handiest number. When an error has arisen through a transposition of figures —about the most common error that is made — can be seen at once by dividing the amount short by nine. Invariably it comes out exactly. Suppose an error occurs in bringing out a cash settlement or a trial balance. If the amount short is divisible by nine, it is a hundred to one that a transposition of figures is the cause. Suppose 69 has been put down instead of 96, the deficit will be 27, "divisible exactly by nine; or that 523 has been put down for 253; the surplus will be 270, also divisible exactly by nine. This holds for any transposed numbers. Producing Paper. A thin grey fluid comes bubbling out of the vat on to the straining table, and spreads upon the smooth surface of the wire cloth. This fluid is 98 per cent, water and two per cent, cellulose from wood pulp. The main operation is to extract that 98 parts of water and roll and dry and press the “web” into the material on which is printed this little article, and in a modern paper manufactory the whole operation takes but three minutes. At the far end a sheet as much as 12ft wide is rolled out at a steady rate of 500 ft a minute. A roll of paper 100 miles long without a single break was once made at a paper mill at Sittingbourne in Kent, and there is one factory which turns out 30,000 tons of writing paper yearly, and every day 150 miles of wallpaper. Nearly all our common and printing paper is made of wood pulp. So tremendous is the demand that the supply is running short, and paper is constantly rising in price in consequence. An average spruce tree makes 5001 b weight of pulp. A big newspaper will use as much as 150,0001 b weight.of paper in a single day, so that to produce one day’s edition no fewer than 300 trees are required. This means the stripping of twj acres of forest. In the course of a year such a paper uses up nearly a square mile of trees which have taken fifty or sixty years to grow. Effects of Weather on Health. Have you noticed how the weather affects your health? Doctors are realising more and more that changes of weather cause changes in the human body. They say that sunshine and rain, cold and heat, are important factors in our health.. The study of the relations between health and weather has become a new science, which is called “climatology.” Different kinds of weather affect different people in different ways, but as a rule we feel better when the sun is shining. Damp

is an enemy of health; a cool, bracing a friend. Doctors frequently order their>' patients a “change of scene,” and they are - now learning that the benefits of such a change are greater even than they had. ,thought, because a change of scene usually means a change of climate as well. 'Ternperature, the amount of moisture in the air, the height above sea-level —all these things can affect our health. Not only has weather a direct influence on our health, hut an indirect one also. Our lives are arranged to suit the weather and climate. Dad weather keeps us indoors, and consequently, in winter, when darkness ham- * pers our movements in'the open air, many of us lead unhealthy lives. Another discovery made by “ climatologists” is that sunshine has a wonderful healing effect in such diseases as tuberculosis and rickets. The direct rays of the sun on our bodies form a treatment which is being given more frequently every year. In the same way, the study of weather reports has become of increasing importance in deciding the situation of hospitals, sanatoria, and convalescent homes. An Automatic Pilot. The Berengaria, on which the Prince of Wales travelled to America, is one of the largest boats fitted with the automatic quartermaster or gyro-pilot. Briefly, the system practically eliminates __. the errors common to human judgment irT/y the steering of a vessel, and once the course is setwhich is effected by turning a small wheel to the desired degreethe master gyrocompass may be considered as in charge of the ship, though there is always a man at the wheel to deal with emergency conditions. • It is seldom, however, that he is more than a passive onlooker of a wheel that in a curiously uncanny manner turns itself to. the required extent, and thus compensates for the effect of both wind and waves as they tend to deflect the ship from her course. The secret of the control is contained in the master compass, which may be placed in any part of the ship, and operates an electrical circuit whenever the bow deviates from the appointed route. The rudder, obedient to the compass, corrects the deviation and, having done so, returns to normal. ' The master compass, apart from steering the vessel, operates “repeater compasses” on the bridge or elsewhere, and at the game time makes a permanent record on a moving chart of each deviation of the ship, whether under automatic or human control.