TWELVE MILES IN THE AIR.

Dominion, Volume 6, Issue 1732, 24 April 1913, Page 4

TWELVE MILES IN THE AIR.

METEOROLOGICAL BALLOONS. INTERESTING EXPERIMENTS. During the next week or (wo an interesting series of experiments will be begun by the Government Meteorologist (Mr. 11. A. Hunt), with the object of testing the barometric pressures and temperatures of the upper atmosphere (says the "Sydney Morning Herald"). It is obvious that one needs special apparatus' to earr.v the recording instruments into tho outt'i- regions of the air. beyond the highest cirrus clouds, out to where there can he no highly organised life, because of the dimimiation of the air-pressure. The apparatus to be used consists of small rubber balloons, filled with hydrogen aas. These balloons are used in meteorological work in Europe, and have been for some time, but the ascents of the next fewweeks will be the first of the kind in Australia. Naturally, when science deals with the ebb and How of atmospheric currents, it must have data, not only of (he currents in the lower atmosphere, but of the whole gaseous envelope of the globe. Wind is not confined to the surface, and though tho temperatures diminish the higher one goes, there has been discovered a region in the outer boundaries of our air \yhero, before the filial fall into the awful cold of space, there is an actual rise in temperature. What is the fauso. of this has lint yet been determined, and very little is known about it. But (here it lies, an interesting and mysterious stratum, which human beings themselves will never roach; .but which may bo entered by these miniature recordine balloons. i ■

The balloons are of the best rubber, and weigh about 12oz. Beside these larger ones, which, expanded, reach a diameter of about a yard, are smaller ones, used as pilots, liberated for the purpose of watching the direction of the air currents, and judging,\in some measure, tho position of the fallen balloon, with its instruments, after its (light into the upper air. The larger balloon has attached to it a cane and siring contrivance, weighing an ounce or two, and. to the centre of this skeleton cube, or "spider," is lashed the aluminium cylinder containingtlie registering instruments. This "spider" is used jso that, by its great elasticity, (he impact of the fall from a height of about GO,OOO feet will not shatter the recording apparatus. It consists »f two light canes, about 3ft. lonpr, lashed at right angles, then nt right angles again lo the plane of tho square thus formed, a third similar cane. The ends are joined tip by means of strong twine.

The recording instruments arc wonderfully ingenious in their effectiveness and adaptability for the purpose intended. They weigh,' perhaps, another two or three ounces, and consist of a rough aneroid, actuating a style, and a bar of metal, with a high expansion to heat, terminating in another style, both of which points move across a frosted aluminium surface, scratching out the records of pressure and temperature. The, 'instrument is calibrated in ft special box, under intense cold and a high degree of atmospheric exhaustion, and at known temperatures and pressures marks are made on tho recording surface before, tho apparatus is launched into the air. These marks serve, of course, as points of measurement for tho final reHilts.

The spider is.attached to its balloon, ivhich is distended with hydrogen gas to doublo its normal diameter, <and the whole apparatus rushes up upon its tremendous twelve-mile journey. As it rises, pud the pressure around the gasbag fails, the bag itself becomes further distended,, until, at tho awful height of about GO,oooft., the limit of elasticity is reached, and the bag bursts. The instruments fall, attached to their spider, having scratched the rccords on the recording surface. By moans of a telescope, it is possible to trace the whole journey. But, naturally, tho fall may take plaeo nanv miles from file point of ascent, and here is where tho duty of tho public conies in. Tho aluminium ease of instruments' is labelled with a rtmiest for return to the Meteorological Bureau, and, as the records will bo of high scientific value, it is confidently expected by Mr. Hunt that any person finding the instruments will return them, without damaging them, to tho bureau. The whole c-f tho apparatus is now ready, except f<ir the gas generator, which should soon bo finished, and then the "experiments will begin, the first of the balloons being dispatched from the Meteorological Bureau. Later on, to investigate the lower strata, at from 3000 ft. to 5000 ft.,' Mr. Hunt intends to uso the weather kito system at 'lie Federal capital, but tho apparatus for this is very costly, and has not yet been purchased. Tho" balloons, howoyer, are cheap, and, while they cannot give as complete records as the* kites, yet, if tho public assists tho bureau by. returning the instruments when found, the results should bo very valuable and interesting.