SCIENTIFIC BALLOONING. 311 



but again took the former direction due to the higher current. After 

 three hours the coast of Sussex was sighted fast approaching, and it 

 became a question in the mind of the aeronaut, Mr. Percival Spencer, 

 whether it would be practicable to cross the channel. The project was 

 eventually abandoned, but not until the outskirts of Hastings were 

 reached, and the old part of the town lay right ahead, stretching down 

 to the bare cliff. At this point, therefore, it might have seemed impos- 

 sible to avoid either d-escendiug on the house tops or being carried out 

 to sea. The altitude was over 8,000 feet when Mr. Spencer first pulled 

 the valve rope, and the houses were already vertically underneath. The 

 descent not being rapid, the balloon still sped seaward until it neared 

 the forest of chimney stacks around. Here, however, it was caught 

 by a breeze blowing stiffly from the west, and rapidly clearing the town 

 was brought to earth in Fairlight Glen. The stratagem was simply a 

 display of perfect judgment on the part of the aeronaut, who, noting 

 and calculating accurately the ground current, had piloted his craft to 

 a convenient spot which he had fixed on from nearly 2 miles high. 



As may be presumed the depth of different currents varies vastly, 

 but it is very common to meet with a change of direction before the 

 first thousand feet is reached. Since, then, such fluctuations are all 

 important, and also all primarily due to relative temperatures, it 

 becomes the first care of the scientific aeronaut to record continuously 

 all changes of temperature observed at different heights, on different 

 days, and at all hours of the day and night. For, regulated by such 

 differences of temperature, seen or unseen columns of warm moist air, 

 or mist, will constantly rise off valleys, or woods, or crops, while return 

 supplies of cooler air will filter down to earth from above, and in this 

 way a remarkable condition of the atmosphere, which needs to be 

 investigated to be fully realized, may be brought about. 



Late in the evening and far on into the night the explorer of the 

 upper regions may encounter, at varying and uncertain heights, tracts 

 of warm and genial air whose existence could not be detected from 

 below, or, indeed, from any observations made on mountain slopes. 

 Mr. Glaisher gives an interesting experience of an ascent of some 

 0,000 feet which he made over verdant Surrey, on a late May evening 

 just before sunset, and repeated again immediately after sunset. 

 Starting on the second ascent at ten minutes past 8 the temperature 

 was 54°, and on his ascending this steadily declined, but not so rapidly 

 as in the ascent prior to sunset, so that at the height of 6,200 feet the 

 temperature, though only 35°, was 6° warmer than it had been three- 

 quarters of an hour previously. On descending to 4,500 feet, however, 

 it had increased to 37°, from which point it went up by leaps and 

 bounds, registering 47° at 1,500 feet and 54° at 900 feet, below which 

 height it again declined till earth was reached. 



In a night ascent at the end of September the present writer 

 recorded similar, though somewhat more changeful, observations. 



