Science.

Alexandra Herald and Central Otago Gazette, Issue 403, 28 January 1904, Page 7

Science.

THE AIB." yj£JSKHE smoke from the great volcanoes wm(Q i a other hemisphere constaatly Cfl&s blows to the Treat, showing that the trade wind in that part of the world is a current at least 15,000 ft thiok, On the Peak of Teneriffe the clouds which form against its summit stream off in a direction contrary to that of the wind at sea-level. The cnriouß fact has been noted that the mean lower limit of this anti-trade wind is greater in summer than in winter. In October it sinks to 6 000 f t; in May it is 9000 ft. Bat in these islands, and in .most other places, there are no mountain peaks sufficiently lofty to give similar information about the upper air currents. In any case, what mountains tell is a very small portion of the information we want about the great aic sea, at the bottom of which we live.

Man has sounded the utmost depths of the ocean, bnt sounding the air is a much more difficult problem. We shall probably never know for certain how deep the atmosphere is. A few years ago forty miles was. supposed to be its limit: At present it is fairly certain that there is some air as much as 500 miles from the earth's surface. This information has been gained by watching meteors. Since it is impossible for man to sustain life at a height of more than six and a half miles above the earth, weather experts have taken to the use of small trial balloons, which carry no passenger, but several self-registering instruments, by means of which the temperature, pressure, and amount of moisture in the air are automatically recorded. Up till quits recently these balloons were made of silk and cost £25 each. Now, however, it has been found that varnished paper does equally well. Small balloons of paper cost only £2 10s., just one-tenth the expense of the silk. One of these trial balloons, sent up recently by M. de Bort, director of the Txappes Observatory, reached the amazing height above the earth of 45 OOOffc, and its thermometer was found to register a cold of 103 degrees below zero, Fahrenheit, which is about 30 degrees balow the extreme of Polar winter weather.

More than ,£4OO was the price paid for a small trial balloon recently purchased by the French Meteorological Department;, for the purpose of testing the weather of the Sahara. As tbe trip is expected to test four or five day a, the instrument is fitted with elaborate clockwork nuchiaery to operate them for five days, Also a camera is carried with a long strip of film. It is so arranged that an exposure will be made once every quarter of an hour. Leakage of gas is to be balanced by wAte? ballast. A. ball hangs below the car, and whenever it touches ground a valve is opened, and a certain amount of water released

Among the many curious f aots discovered by means of balloons is tbe point that at a certain height the temperature no longer falls, bat remains constant-—or, indeed, Gometimes rises, The point of greatest cold is, in winter, about 30,009ifci in summer, about 33,000 ft. And at this height-it appears that violent winds are quite unknown. The air on steadily and qui&lly. Balloons being; expensive and very unreliable, as it is impossible to construct a gas envelope that will not leak, the latest invention for probing the air is the boxkite. The American meteorologists rely almost entirely upon kite observations. Profesßor W. L. Moore began in 1808 the most complete survey of the upper air ever A number of different stations were equipped with kites, and self-recording insfcumants were sons up every day when possible. The Blue Hill Observatory has the biggest kite. It oojitaias 70 square feet of surface, and its pull in a breeze is fully 1001b. No m»n. could manage it, so a steam - windlass is, used, which unreels and raels in again the steal wke which holds the kite. This wire is no thicker than a pin; but will stacu a strain of 3001b. The metjorgrapb. which these kites carrycottains so fewer than five self-registering instruments, yet weighs only 2ib. It is chiefly made of aluminium. When it is wished to attain great heights, a team of kites is used.- By using three on tne same wire, a height of IB.GOOIt has been reached frequently; and oace 15,000 it, or more than three miles above sea-level, was attained. -,: -■ - '..->;''

Many points of great interest have bees discovered by kites. The Blue Hill kite, when tbe sea-breese is blowing, ascends

1,200f>, and than direction. Above that ourrent is blowing. -•-V^IS! Everyone baa noticed cuinalus clouda which fly up rapidly across .•a. summer- sky. These' : covered, exercise always a - poll. When, a kite approaches a c|du<if of-, this sort, it makes a tremendous jump upwards. ' Temperature readings secured by kites prove tons that the layers of hot Air during the great heats'of summer are usually no more than 500 ft thick—that is •on the hottest day an ascent of 500 ft only ; would place one in a comfortable tarnper&ture. The layer of ohMed which! causes a froßt in winter is usually far thicker; yet on soveral occasions a thermometer sent up when the ground was covered with snow and lee has' recorded a temperature lOleg; to 15deg. above freezing-point at a height of 2000 ft, ■>