Science Siftings

New Zealand Tablet, 17 August 1916, Page 45

Science Siftings

By 'Volt.'

Accurate Timekeeper. ■'« A ship's chronometer is %he most wonderful and accurate timekeeper made, for upon its accuracy depends the lives of all on board. So accurate, indeed, is a ship's chronometer that it does not vary a second a day. An error of only a few seconds may put a captain of a vessel miles out of his reckoning at sea, and run the ship into great danger. For that reason every ship's timepiece goes through the most thorough tests before it is pronounced perfect. It is set going in a very hot room and then transferred to a cold one, for it may be used in any part of the world, from the Polar regions to the Tropics, and it must always keep good time., Most large vessels have three chronometers on board-in case of accidents, and whenever a vessel goes into port they are sent on shore and tested to see if they are still accurate. On board ship the chronometer is kept amidships because there is the least motion and the smallest variation of temperature. Zeppelins and Their Speed. Not so many years ago a British expert calculated that the Zeppelin could not attain a speed of thirty miles an hour, as he proved by figures that the ship would collapse under the air pressure.. To-day the tendency is (says Mr. R. P. Hearne, an authority on the subject) to attribute too high a speed to the vessels. In still air it is doubtful if a higher speed than sixtyfive miles an hour can be reached, and by the most careful calculation I have come to the conclusion that the average speed of the modern Zeppelin in war trim is about forty miles an hour with full load. Of course, with a favoring wind the ship may often be running at over sixty miles an hour, and the difficulty of gauging wind speed often causes erroneous estimates of Zeppelin speed by observers on land. In the upper regions where an airship is moving there may be a strong current, whilst near the earth there is a calm. It is well to note that for a short period a Zeppelin can climb faster than an aeroplane. By throwing out ballast, going full speed ahead, jamming the tail down and shoving the nose up, a Zeppelin jumps a thousand feet or so in about half a minute. This rate of climb, however, cannot be maintained Canal Systems. An expenditure of some twenty odd millions is suggested for the widening, deepening, and extending the canal system in Great Britain, in order to provide for barges of 100 tons capacity, over some 4000 or 5000 miles of inland navigation. There are splendid inland waterways on the Continent7ooo miles in Germany, and a similar mileage in France. Fine barges of 150 tons, and even 300 tons capacity, carry goods at an extremely low cost and at a very good speed, and it is assumed that what is done in those countries can be done in Great Britain. But canal advocates do not pay sufficient attention to the physical differences between England and Scotland and those parts of the Continent which are so well served by canals. In Germany, France, Belgium, and Austria the chief industrial districts served by inland waterways are comparatively flat, and possess fine rivers naturally adapted to canalisation, whereas all the way from Scotland to the Peak of Derbyshire we have the Pennine Chain. In industrial Scotland, Durham, West Yorkshire, and South' Wales there is hardly a bit of level country or a river naturally suitable for navigation. Even in the short distance between Birmingham and Worcester there are fifty-eight locks.