Science Siftings

New Zealand Tablet, Volume XXXVII, Issue 9, 4 March 1909, Page 355

Science Siftings

BY 'VOLT

The Panama Canal. Mr. Joseph B. Bishop, secretary of the Panama Canal Commission, states that the canal will be opened on January 1, 1914. He says : ' There has been excavated from the line of the canal since the Americans took control about 56,000,000 cubic yards. This, as near as can be calculated at the present time, is about one-third of the entire excavation necessary to complete the work. In 1908, down to November 1, nearly 31,000,000 cubic yards were removed and the total for this year will not be far from 37,000,000 cubic yards. The average is between 36,000,000 and 42,000,000 cubic yards a year.' A Billion. What a very great sum is a billion ! (says an exchange). It is a million of millions. A million seems large enough — but a million of millions ! How long do you suppose it would take you to count it? A mill which makes 100 pins a minute, if kept to work night and day, would only make 52,596,000 pins a year — and at that rate the mill must Avork 20,000 years without stopping a single moment, in order to turn out a billion pins ! It is beyond our reach to conceive it, and yet, when a billion of years shall have gone, eternity will seem to have just begun. Hoav important, then, is the question, ' "Where shall I spend eternity?' To Dispel Fog. Sir Oliver Lodge's plan for dispelling fog, Avhich is to be tried on a large scale near the Grosvenor Canal, is an interesting example of the practical application of science. The method consists in passing a current of electricity at high voltage through the fog-laden air. It has been successfully tried on a small scale. Whether it can be carried on a large scale at a sufficiently moderate cost, and with sufficiently permanent results, now remains to be seen. The discharge of a current of electricity through a dustladen atmosphere, it is Avell known, causes the dust to settle, and leaves the air clear. Fogs, again, are due to the condensation of the moisture of the air round dust particles. Thus the discharge of electricity through a, fog causes the dust particles with their inherent moistiue to settle, and so disperses the fog. The question then arises, Would it not be feasible to clear the atmosphere of a city periodically of its dust in this way, without waiting for the formation of a fog ? A New Fire Alarm. Mr. L. T. Reichel, Chief Electrician, Public Works Department, Wellington, has invented a fire alarm which is not only new in principle, but also in method of operation, and the inventor claims for it advantages possessed by no other automatic alarm. The usual method (says the Wellington Post) is to cause an automatic alarm to be set in motion by the action of a rising column of mercury in a thermometer. In such a case, to obviate false alarms, the contact temperature must be fixed someAvhere near the maximum of the room. Mr. Reichel's plan is different. His instrument ignores steady rising and falling temperatures, marking only sudden changes such as are not likely to occur in the regular course. Its essential feature is a thermostat consisting of a series of thermocouples in the form of a rosette. If two strips of unlike metals are connected at one end, and so heated that the ends in connection vary in temperature from the opposite ends, an electric current is set up, and Avill fIoAV so long as the respective temperatures vary. In Mr. Reichel's thermostat one metal is exposed to the atmosphere. The other is buried in plaster, and a sudden change in the temperature, affecting one metal only at first, establishes a current direct, obviating all intermediate apparatus. The rosette of thermo-couples is wired to an indicator-board fitted with a galvanometer; a change in the temperature sets up a current — right or left, according as it rises cr falls. A fall is not indicated on the alarm, but a sudden rise, though no more than a degree, causes an electric contact being maintained by a magnet, the bell rings till it is stopped. The actxial temperature of the room in no Avay affects the instrument. Each thermostat is connected Avith the indicator, and one indicator may serve for six or eight rooms, may vary in actual temperature — as a matter of fact, there were variations of seventy degrees and more in the experiments, but it is only a rise that' is registered.