Science Sittings

New Zealand Tablet, 4 October 1906, Page 35

Science Sittings

By 'Volt*

The Age of an JEgg. - , • A simple method of finding out the age of an egg is by means of the air space, which is situated towards the broad end of the shell. If the egg is held up between the hands 'before a light in a- dark room, the air space can easily be discerned, and by its size the age can be determined. In a perfectly fresh egg the air space is very small, but as age ' increases it extends, until when the egg is three weeks old the air space occupies about a sixth of the entire contents. With practice the age can be told to within twenty-four hours. Working Under Water. In the interests of science men are greatly daring. Messrs. Leonard Hill and M. Greenwood, two wellknown engineers, lately determined to investigate the effect of working under compressed air, but instead of collating experiences of others they made stays themselves in a cylinder loaded up to various pressures. They underwent a pressure of 9211b s above the atmosphere, corresponding to a head of 212 feet of water. They had one effect which workers would not suffer— neuralgic pains caused by their remaining quiescent,; whereas it is of the utmost importance that every joint and muscle should be kept in motion, and the capillary circulation kept active. .As a result of the experiments the two investigators have come to the conclusion ithat work may be safely carried out in 212 feet of water, or perhaps even 250. At 16 lbs air pressure the voice becomes metallic, and at 45 they found it impossible to whistle. Hearing was very acute, and after the nervousness had worn off there was no feeling of pressure during a fifty minutes' stay in the cylinder. Devices for Catching Mice. Not knowing what else to do with its vast accumulation of models, the Patent Office at Washington is about to disperse the collection. Under the patent law every applicant for a patent must submit a model of his invention. Of models of patent mousetraps alone there are no fewer than 1810, and the hundreds of thousands of models of every conceivable invention have filled to overflowing the 'old Post Office buildings. It has been determined not to be worth while to erect new storehouses for the mass of material, the bulk of which tis rubbish. The Government will preserve the models of really great inventions, such as the first sewing machine, the original telegraph instrument, or the first threshing machine, and similar devices that mark eras in the country's development, and many other models will probably go to colleges and technical schools. There is a fine chance for curiositymongers to pick up freaks of ingenious inventors, but the great mass of the models is doomed to a holocaust. A True Clock. The most mathematically exact thing created by man, and the perfection of accuracy in registering the flight of time is the famous Reifel clock, which has been installed in seven of the observatories of the United States. This clock, which costs £200, is enclosed in'an airtight case in a vacuum. It is wound up every seven minutes by electricity to keep it always under the same pressure, and has a nickel steel pendulum that does not expand or contract under the changing atmospheric conditions 51,000 of a" degree of a second. The one at Washington stands in a room which is almost a dungeon, being heated by electric lights, so that there shall not be as much as a hairbreadth change in the temperature registered . on the microscopic thermometer. - And still this clock is not as perfect as one created ages ago, and which- was khown to earliest man— the earth is the only perfect clock. If we take the position of a fixed star at a certain moment of time to-night we know that ex-_ actly at that corresponding moment to-morrow the earth, in its revolution, will arrive at the same point, and will not vary as much as even 1/000,000 part of a second.. And still, again, the earth is ' not wholly exact, as it has been estimated that pur day is 1-84 of a second longer to-day than it "was 2500 years ago. This is due to the tremendous effect of the tides in the revolution of the globe from east to west.