11-" 



METEOROLOGY. 



BAU.OOX AHCEXT. 



observer <mn reach any altitude he may desire ; he can 

 scend and descend a* be pleases ; hi* attention need be 

 diverted by no object ; and be is put to no personal 

 inconvenience. Several asoenU have been made ; and we 

 select the following account (furnished by Mr. Glaisher, 

 of the Royal Observatory, Greenwich) of one made on 

 July 30, 1862. 



' Mr. Coxwell having planned an ascent with his large 

 balloon, from the Crystal Palace, I availed myself of the 

 offer of a seat in the car, for the purpose of taking a 

 series of observations upon the variations of temperature, 

 and the several hygrometrical states of the atmosphere at 

 moderate elevations, and which I had failed to do in my 

 recent ascent from Wolverhampton. 



"The instruments necessary for these investigations 

 were in the hands of Messrs. Kegretti and Zambra, and 

 were those which wore broken and injured in my recent 

 ascent with the same balloon, and confided to them for 

 renewal and repair, and which they had executed in a very 

 satisfactory manner, these gentlemen having, at all times, 

 expressed an earnest desire to promote the experiments 

 required by the British Association. All the other in- 

 struments are at Wolverhampton, ready for the next high 

 ascent. The instruments used on this occasion were two 

 aneroid barometers, dry and wet bulb thermometers, and 

 a Darnell's dew-point hygrometer. As it is of essential 

 importance that the thermometers should be so sensitive 

 that they readily acquire the temperature of the sur- 

 rounding air, they were of necessity very delicate. 



"The air was in very gentle motion, which enabled 

 Messrs. Negretti and Zambra carefully to fix the instru- 

 ment* before starting, so that I at once began to observe, 

 which in my former ascent I was unable to do until I 

 was the greater part of a mile high. 



"The balloon left the earth at 4h. 40m., laden with 

 thirteen gentlemen, and a largo amount of sand for 

 ballast, and, under the influence of a moderate breeze, 

 bore away slowly nearly S.E., passing successively 

 Eltliam, Dartfonl, to the village of Singlowell, near 

 Gravesnnd. 



" The heights of the balloon, successively, wore as 

 follows : At 4h. 43m. it had attained the elevation of 

 1,340 feet above the level of the sea ; at 4h. 49m. that 

 of 3,700 feet, increasing slowly, till, at 5h. 17m., it was 

 about 6,300 feet It then, by 5h. 20m., fell 200 feet. 

 On throwing out sand it rose to 5,500 feet by 5h. 24m. ; 

 and to 6,600 feet by 5h. 43m. Some gas was let out, and 

 it sank to 5,700 feet by 6h. 47m. Some sand was 

 then thrown out, and it rose to 7,350 the highest point 

 reached at 6h. 1m. At Gh. 6m. it fell to 6,700. Some 

 sand was thrown out, and it rose to 7,100 feet by Gh. 

 12m. At twenty minutes past six it descended to 5,300 

 feet, and slowly to 2,100 feet at 6h. 25m., and to the 

 earth a little after half -past six o'clock. 



"Between 4h, 46m. and 5h. 1m., the altitude and 

 azimuth of the balloon were observed at the Royal 

 Observatory, Greenwich, by E. J. Stone, Esq., M.A. 

 If any similar observations havo been taken at another 

 place, I should be glad to be favoured with them, as 

 furnishing the means of an independent determination 

 of the elevations of the balloon, and thus checking those 

 made by means of the variations of temperature and 

 barometric pressure. 



" The temperature of the air was 68 at the Crystal 

 Palace. At 1,000 feet high it was 62 ; at 3.700 feet it 

 was 61; it continued at this reading nearly till the height 

 of 4,600 feet was reached. At 6h. 4m. it varied between 

 48 and 50, till the height of 6,700 ; it decreased from 

 48 to 43J between 6h. 31m. and 6h. 38m. ; the height at 

 the hitter time being 6,100 feet. At the height of 7,360 

 feet the temperature was 41, being 27 lower than on 

 tho surface of the earth. After this the temperature 

 rose gradually as tho balloon descended, and was 47 

 at Oh. 20m., 60' at Oh, 24m., and 68 on reaching the 

 ground. 



" The temperature of the dew-point, or that tempera- 

 ture at which the moisture in the air, in the invisible 

 * h *P!i * Ta P ur > ** deposited as water, upon the objects 

 cooled down to this temperature, were successively as 



follows : In the gardens of the Crystal Palace this 

 deposit of water took place when the temperature of 

 the bulk of the hygrometer was reduced, by the action of 

 ether, to 60; at the height of 1,300 feet tho bulb was 

 bedewed at 43"; between 3,000 and 4,600 feet, at 40; 

 then up to 6,000 feet, at temperatures gradually decreas- 

 ing; at about 7,300 feet, at a little below 32; and it 

 afterwards increased to 47 on reaching the surface of 

 the earth. When the air is saturated with moisture, as 

 in a wetting fog, the temperature both of tho air and 

 dew-points is the same. On this occasion, on the earth, 

 the hitter temperature was 18 below the former, and at 

 tho highest elevation was 9, so that the air was nowhere 

 saturated. From a knowledge of tho temperature of 

 the dew-point, we know the amount of water then pre- 

 sent in a certain mass of air ; this amounted, in tho 

 grounds of the Crystal Palace, to 4 grains in a cubic 

 foot ; at 1,300 feet high, to 3 grains ; at 5,000 feet, but 

 2} grains ; and at 7,300 feet, there were about 2 grains 

 in a cubic foot of air. 



" As the amount of aqueous vapour in tho air neces- 

 sarily decreases with the temperature, the changes of tho 

 hygronietric condition of the air, at different elevations, 

 may be better understood in speaking of the relative 

 humidity of tho atmosphere, by considering air as 

 saturated with moisture represented by 100, and air 

 without moisture by 0. 



"The humidity of the air thus expressed was, on the 

 surface of the ground, 50, showing an unusual degree of 

 dryness. It increased as we left the earth to 63 at 3,000 

 feet, to 66 at 4,000, and to 70 at 7,300 ; and the air 

 gradually became less humid on approaching the earth. 

 At no point, therefore, was complete saturation met 

 with, as before noticed. The weight of a cubic foot of 

 air varied from 626 grains on the ground, to 429 grains at 

 the greatest height reached. 



" Similar and simultaneous observations were taken 

 at the Royal Observatory, Greenwich, from which wo 

 learn that the temperature of the air, on tho surface of 

 the ground, varied from 67 to 68; that of the dew- 

 point from 49 to 51; that there were about 4 grains of 

 water in a cubic foot of air ; the degree of humidity 

 was about 60 ; and the weight of a cubic foot of air was 

 626 grains : therefore the differences at tho highest 

 elevations, from these values, are due to the elevation 

 alone. 



"Test ozone papers were not coloured at all; and no 

 ozone was noticed in tho ascent from Wolverhamptou.* 

 We were never in the clouds, although rocky cumuli 

 which, it will be remembered, are the line massive clouds 

 of day were at a lower elevation all round, and cuniulo- 

 strati at a higher elevation than ourselves. The sky was 

 free from clouds in the zenith, and of a deeper blue than 

 as seen from the surface of the earth. At times there 

 was a great mist, and, generally, the horizon was hazy 

 and obscure ; the shadow of the balloon was seen both 

 on the ground, as well as on tho surface of tho 

 clouds. 



" A horizontal magnet occupied a somewhat longer 

 time to perform a certain number of vibrations, both in 

 this as well as in the previous ascent, than it did on tho 

 surface of the earth. This is contrary to the result 

 obtained by Guy Lussac in 1804. 



" At 5h. 24in. a gun was heard with a sharp sound ; 

 at lih. 25m. a drum was heard ; at 5h. 26m. a band was 

 heard ; at 6h. 38m. a gun was heard ; and at (ih. 10m. 

 a dog barking was heard ; and tho working of the 

 engines, on the Dover and Chatham Railway was dis- 

 tinctly heard. 



"I have to thank W. F. Ingelow, Esq., for kindly 

 reading one barometer for me, and for rendering con- 

 siderable assistance in noticing the first appearance of 

 dew on the black bulb of Danicll's hygrometer, enabling 

 mo thereby greatly to increase the number of my own 

 observations. The gas furnished must have been of 

 good quality to havo raised so groat a weight to such an 

 elevation." 



Mr. GUInher lUtn, rabtequentljr, that thii wu owing to the ptpcr- 

 IctU being of bad quality. 



