Science Siftings

New Zealand Tablet, 9 March 1916, Page 55

Science Siftings

By 'Volt.'

f : .. Why You Sneeze. There is more than one cause for -sneezing, and persons may differ in their susceptibility to them. A bright light will cause some persons to sneeze, the pol- '• len of certain plants will affect others, and most people. are likely to sneeze in the presence of dust. Such sneezing is due to superficial irritation. The sneeze caused' by the effect of cold is different. It-is an attempt of Nature to cure you. She makes you sneeze for the'same,reason that she makes you shiver—to generate heat for warming the blood and preventing you from taking more cold—to help to relieve the cold you have. The sneezing from cold is not an act of the nose alone, this being merely the part of the body where it explodes. It is an act of the, entire body, during which every muscle gives a jump. The body is affected by a .spasmodic effort to warm the entire system and throw off cold. ■ World's Largest Lighthouse. ' The most important lighthouse at the present time, so far as actual• operations arc concerned, is the light of Heligoland, from the fact that it is centred in the very heart of the naval war zone. Heligoland was ceded by Great Britain to Germany in 1890, in return for concessions made to Britain in East Africa. The 'Heligoland light is an electric one, and the most powerful in Germany, and is claimed by the Germans to be the most powerful light in existence. ' The light consists of a cluster of three revolving lights, having a lighting power of 40,000,000 candles, a magnitude of light which from figures .alone is hard and difficult to realise. The lights are on the searchlight principle, and the cluster is surmounted by a single light of the same kind and size, that can be revolved independently and three times as fast as the three lights. The single light is put into use in case of accident to the cluster of three. The electric power is generated by two steam-engines and boilers, running belt-driven electric generators. Lungs of a Battleship. One of the most difficult problems in building a . modern battleship is to secure satisfactory ventilation. She is such a complicated creature, made up of so many steel boxes, large and small, for the accommodation of officers, men, coal, ammunition, and stores; dotted here and there with so. many steel ladders,'automatic lifts, steel bulkheads, and water-tight doors, varied here and there by miles of electric wires belonging to lights, telephones, bells, and motors, to say nothing of the endless mileage of pipes for flooding, draining, pumping, fresh water, fresh air or compressed air, and speaking-tubes. First in importance comes the ventilating of the boiler and engine-rooms. When you begin to think of gangs of coal-black demons working away in the bowels of the ship at a temperature of 120 degrees when, too, you commence to realise that unless the furnaces receive their required draught the speed of the battleship drops to below that of her sisters in the squadron, you appreciate the importance of the steam-driven fans .to the furnaces and boiler-rooms. The sunoly of air comes down through large water-tight trunks which are continued right up to the. weather-deck, armored gratings being provided at the protective deck. For ventilating engine-rooms, large electric fans are employed. _ So, too, the coal bunkers have to be ventilated, owing to the gas which the coal gives off. This gas when mixed \ with air forms an explosive; so, in order to prevent the possibility of injury to men or ship, a supply, and an exhaust-pipe are fitted in such a manner as to caase a current of air. \, ■'. .'• -". ; .'■