the dominion of the air-第61章
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rvice； the writer； in the early part of the present year； suggested to the Admiralty the desirability of experimenting with balloons as a means of detecting submarine engines of war。 It is well known that reefs and shoals can generally be seen from a cliff or mast head far more clearly than from the deck or other position near the surface of the water。 Would not； then； a balloon； if skilfully manoeuvred； serve as a valuable post of observation？ The Admiralty； in acknowledging the communication； promised to give the matter their attention； but by the month of June the Press had announcements of how the self…same experiments had been successfully carried through by French authorities； while a few days later the Admiralty wrote； 〃For the present no need is seen for the use of a captive balloon to detect submarines。〃
Among many and varied ballooning incidents which have occurred to the writer； there are some which may not unprofitably be compared with certain experiences already recorded of other aeronauts。 Thunderstorms； as witnessed from a balloon； have already been casually described； and it may reasonably be hoped that the observations which have； under varying circumstances； been made at high altitudes may throw some additional light on this familiar； though somewhat perplexing； phenomenon。
To begin with； it seems a moot point whether a balloon caught in a thunderstorm is； or is not； in any special danger of being struck。 It has been argued that immunity under such circumstances must depend upon whether a sufficiently long time has elapsed since the balloon left the earth to allow of its becoming positively electrified by induction from the clouds or by rain falling upon its surface。 But there are many other points to be considered。 There is the constant escape of gas from the mouth； there is the mass of pointed metal in the anchor； and； again； it is conceivable that a balloon rapidly descending out of a thunderstorm might carry with it a charge residing on its moistened surface which might manifest itself disastrously as the balloon reached the earth。
Instances seem to have been not infrequent of balloons encountering thunderstorms； but； unfortunately； in most cases the observers have not had any scientific training； or the accounts which are to hand are those of the type of journalist who is chiefly in quest of sensational copy。
Thus there is an account from America of a Professor King who made an ascent from Burlington； Iowa； just as a thunderstorm was approaching； with the result that； instead of scudding away with the wind before the storm； he was actually； as if by some attraction； drawn into it。 On this his aim was to pierce through the cloud above； and then follows a description which it is hard to realise：〃There came down in front of him； and apparently not more than 50 feet distant； a grand discharge of electricity。〃 Then he feels the car lifted； the gas suddenly expands to overflowing； and the balloon is hurled through the cloud with inconceivable velocity； this happening several times； with tremendous oscillations of the car； until the balloon is borne to earth in a torrent of rain。 We fancy that many practical balloonists will hardly endorse this description。
But we have another； relating to one of the most distinguished aeronauts； M。 Eugene Godard； who； in an ascent with local journalists； was caught in a thunderstorm。 Here we are toldpresumably by the journaliststhat 〃twice the lightning flashed within a few yards of the terror…stricken crew。〃
Once again； in an ascent at Derby； a spectator writes：〃The lightning played upon the sphere of the balloon； lighting it up and making things visible through it。〃 This； however； one must suppose； can hardly apply to the balloon when liberated。
But a graphic description of a very different character given in the 〃Quarterly Journal of the Royal Meteorological Society〃 for January； 1901； is of real value。 It appears that three lieutenants of the Prussian Balloon Corps took charge of a balloon that ascended at Berlin； and； when at a height of 2；300 feet； became enveloped in the mist； through which only occasional glimpses of earth were seen。 At this point a sharp； crackling sound was heard at the ring； like the sparking of a huge electrical machine； and； looking up； the voyagers beheld sparks apparently some half…inch thick； and over two feet in length； playing from the ring。 Thunder was heard； butand this may have significanceonly before and after the above phenomenon。
Another instructive experience is recorded of the younger Green in an ascent which he made from Frankfort…on…the…Maine。 On this occasion he relates that he encountered a thunderstorm； and at a height of 4；400 feet found himself at the level where the storm clouds were discharging themselves in a deluge。 He seems to have had no difficulty in ascending through the storm into the clear sky above； where a breeze from another quarter quickly carried him away from the storm centre。
This co…existence； or conflict of opposite currents； is held to be the common characteristic； if not the main cause； of thunderstorms； and tallies with the following personal experience。 It was in typical July weather of 1900 that the writer and his son； accompanied by Admiral Sir Edmund Fremantle and Mr。 Percival Spencer； made an evening ascent from Newbury。 It had been a day of storms； but about 5 p。m。； after what appeared to be a clearing shower； the sky brightened； and we sailed up into a cloudless heaven。 The wind； at 3；000 feet； was travelling at some thirty miles an hour； and ere the distance of ten miles had been covered a formidable thunder pack was seen approaching and coming up dead against the wind。 Nothing could be more evident than that the balloon was travelling rapidly with a lower wind； while the storm was being borne equally rapidly on an upper and diametrically opposite current。 It proved one of the most severe thunderstorms remembered in the country。 It brooded for five hours over Devizes； a few miles ahead。 A homestead on our right was struck and burned to the ground； while on our left two soldiers were killed on Salisbury Plain。 The sky immediately overhead was； of course； hidden by the large globe of the balloon； but around and beneath us the storm seemed to gather in a blue grey mist； which quickly broadened and deepened till； almost before we could realise it； we found ourselves in the very heart of the storm； the lightning playing all around us； and the sharp hail stinging our faces。
The countrymen below described the balloon as apparently enveloped by the lightning； but with ourselves； though the flashes were incessant； and on all sides； the reverberations of the thunder were not remarkable； being rather brief explosions in which they resembled the thunder claps not infrequently described by travellers on mountain heights。
The balloon was now descending from a double cause： the weight of moisture suddenly accurnulated on its surface； and the very obvious downrush of cold air that accompanied the storm of pelting hail。 With a very limited store of ballast； it seemed impossible to make a further ascent； nor was this desirable。 The signalling experiments on which we were intent could not be carried on in such weather。 The only course was to descend； and though this was not at once practicable； owing to Savernake Forest being beneath us； we effected a safe landing in the first available clearing。
As has been mentioned； Mr。 Glaisher and other observers have recorded several remarkable instances of opposite wind currents being met with at moderate altitudes。 None； however； can have been more noteworthy or surprising than the following experience Of the writer on Whit Monday of 1899。 The ascent was under an overcast sky； from the Crystal Palace at 3 p。m。； at which hour a cold drizzle was settling in with a moderate breeze from the east。 Thus； starting from the usual filling ground near the north tower； the balloon sailed over the body of the Palace； and thence over the suburbs towards the west till lost in the mist。 We then ascended through 1；500 feet of dense； wetting cloud； and； emerging in bright sunshine； continued to drift for two hours at an average alti
