The Dominion of the Air [122]
through 1,500 feet of dense, wetting cloud, and, emerging in bright sunshine, continued to drift for two hours at an average altitude of some 3,000 feet; 1,000 feet below us was the ill-defined, ever changing upper surface of the dense cloud floor, and it was no longer possible to determine our course, which we therefore assumed to have remained unchanged. At length, however, as a measure of prudence, we determined to descend through the clouds sufficiently to learn something of our whereabouts, which we reasonably expected to be somewhere in Surrey or Berks. On emerging, however, below the cloud, the first object that loomed out of the mist irnmediately below us was a cargo vessel, in the rigging of which our trail rope was entangling itself. Only by degrees the fact dawned upon us that we were in the estuary of the Thames, and beating up towards London once again with an cast wind. Thus it became evident that at the higher level, unknown to ourselves, we had been headed back on our course, for two hours, by a wind diametrically opposed to that blowing on the ground.
Two recent developments of the hot-air war balloon suggest great possibilities in the near future. One takes the form of a small captive, carrying aloft a photographic camera directed and operated electrically from the ground. The other is a self-contained passenger balloon of large dimensions, carrying in complete safety a special petroleum burner of great power. These new and important departures are mainly due to the mechanical genius of Mr. J. N. Maskelyne, who has patented and perfected them in conjunction with the writer.
CHAPTER XXVIII. THE CONSTITUTION OF THE AIR.
Some fair idea of the conditions prevailing in the upper air may have been gathered from the many and various observations already recorded. Stating the case broadly, we may assert that the same atmospheric changes with which we are familiar at the level of the earth are to be found also at all accessible heights, equally extensive and equally sudden.
Standing on an open heath on a gusty day, we may often note the rhythmic buffeting of the wind, resembling the assault of rolling billows of air. The evidence of these billows has been actually traced far aloft in balloon travel, when aeronauts, looking down on a wind-swept surface of cloud, have observed this surface to be thrown into a series of rolls of vapour, which were but vast and veritable waves of air. The interval between successive crests of these waves has on one occasion been estimated at approximately half a mile. We have seen how these air streams sometimes hold wide and independent sway at different levels. We have seen, too, how they sometimes meet and mingle, not infrequently attended with electrical disturbance
Through broad drifts of air minor air streams would seem often literally to "thread" their way, breakng up into filaments or wandering rills of air. In the voyage across Salisbury Plain lately described, while the balloon was being carried with the more sluggish current, a number of small parachutes were dropped out at frequent intervals and carefully watched. These would commonly attend the balloon for a little while, until, getting into some minor air stream, they would suddenly and rapidly diverge at such wide angles as to suggest that crossing our actual course there were side paths, down which the smaller bodies became wafted.
On another occasion the writer met with strongly marked and altogether exceptional evidence of the vehemence and persistence of these minor aerial streamlets. It was on an occasion in April weather, when a heavy overcast sky blotted out the upper heavens. In the cloud levels the wind was somewhat sluggish, and for an hour we travelled at an average speed of a little over twenty miles an hour, never higher than 3,000 feet. At this point, while flying over Hertfordshire, we threw out sufficient ballast to cause the balloon to rise clear of the hazy lower air, and coming under the full influence of the sun, then in the meridian, we shot upwards at considerable
Two recent developments of the hot-air war balloon suggest great possibilities in the near future. One takes the form of a small captive, carrying aloft a photographic camera directed and operated electrically from the ground. The other is a self-contained passenger balloon of large dimensions, carrying in complete safety a special petroleum burner of great power. These new and important departures are mainly due to the mechanical genius of Mr. J. N. Maskelyne, who has patented and perfected them in conjunction with the writer.
CHAPTER XXVIII. THE CONSTITUTION OF THE AIR.
Some fair idea of the conditions prevailing in the upper air may have been gathered from the many and various observations already recorded. Stating the case broadly, we may assert that the same atmospheric changes with which we are familiar at the level of the earth are to be found also at all accessible heights, equally extensive and equally sudden.
Standing on an open heath on a gusty day, we may often note the rhythmic buffeting of the wind, resembling the assault of rolling billows of air. The evidence of these billows has been actually traced far aloft in balloon travel, when aeronauts, looking down on a wind-swept surface of cloud, have observed this surface to be thrown into a series of rolls of vapour, which were but vast and veritable waves of air. The interval between successive crests of these waves has on one occasion been estimated at approximately half a mile. We have seen how these air streams sometimes hold wide and independent sway at different levels. We have seen, too, how they sometimes meet and mingle, not infrequently attended with electrical disturbance
Through broad drifts of air minor air streams would seem often literally to "thread" their way, breakng up into filaments or wandering rills of air. In the voyage across Salisbury Plain lately described, while the balloon was being carried with the more sluggish current, a number of small parachutes were dropped out at frequent intervals and carefully watched. These would commonly attend the balloon for a little while, until, getting into some minor air stream, they would suddenly and rapidly diverge at such wide angles as to suggest that crossing our actual course there were side paths, down which the smaller bodies became wafted.
On another occasion the writer met with strongly marked and altogether exceptional evidence of the vehemence and persistence of these minor aerial streamlets. It was on an occasion in April weather, when a heavy overcast sky blotted out the upper heavens. In the cloud levels the wind was somewhat sluggish, and for an hour we travelled at an average speed of a little over twenty miles an hour, never higher than 3,000 feet. At this point, while flying over Hertfordshire, we threw out sufficient ballast to cause the balloon to rise clear of the hazy lower air, and coming under the full influence of the sun, then in the meridian, we shot upwards at considerable