the dominion of the air-第32部分
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It would seem as if on this occasion； as on the former one； there was some lack of due management； for the car； suspended at a long distance from the balloon proper； acquired violent oscillations on leaving the ground； and dashing first against a tree； and then against a mast； broke some of the instruments。 A little later there occurred a repetition on a minor scale of the aeronauts' previous mishap； for a rent appeared in the silk； though； luckily； so low down in the balloon as to be of small consequence； and eventually an altitude of some 19；000 feet was attained。 At one time needles of ice were encountered settling abundantly with a crackling sound upon their notebooks。 But the most remarkable observation made during this voyage related to an extraordinary fall of temperature which； as recorded； is without parallel。 It took place in a cloud mass； 15；000 feet thick； and amounted to a drop of from 15 degrees to …39 degrees。
In 1867 M。 C。 Flammarion made a few balloon ascents； ostensibly for scientific research。 His account of these； translated by Dr。 T。 L。 Phipson； is edited by Mr。 Glaisher； and many of the experiences he relates will be found to contrast with those of others。 His physical symptoms alone were remarkable； for on one occasion； at an altitude of apparently little over 10；000 feet； he became unwell being affected with a sensation of drowsiness； palpitation； shortness of breath； and singing in the ears； which； after landing gave place to a 〃fit of incessant gaping〃 while he states that in later voyages； at but slightly greater altitudes； his throat and lungs became affected； and he was troubled with presence of blood upon the lips。 This draws forth a footnote from Mr。 Glaisher； which should be commended to all would…be sky voyagers。 It runs thus：〃I have never experienced any of these effects till I had long passed the heights reached by M。 Flammarion； and at no elevation was there the presence of blood。〃 However； M。 Flammarion adduces； at least； one reassuring fact； which will be read with interest。 Once； having； against the entreaties of his friends； ascended with an attack of influenza upon him； he came down to earth again an hour or two afterwards with this troublesome complaint completely cured。
It would seem as if the soil of France supplied the aeronaut with certain phenomena not known in England； one of these apparently being the occasional presence of butterflies hovering round the car when at considerable heights。 M。 Flammarion mentions more than one occasion when he thus saw them； and found them to be without sense of alarm at the balloon or its passengers。 Again； the French observer seems seldom to have detected those opposite airstreams which English balloonists may frequently observe； and have such cause to be wary of。 His words； as translated； are：〃 t appears to me that two or more currents； flowing in different directions； are very rarely met with as we rise in the air； and when two layers of cloud appear to travel in opposite directions the effect is generally caused by the motion of one layer being more rapid than the other； when the latter appears to be moving in a contrary direction。〃 In continuation of these experiences； he speaks of an occasion when； speeding through the air at the rate of an ordinary express train； he was drawn towards a tempest by a species of attraction。
The French aeronaut's estimate of what constitutes a terrific rate of fall differs somewhat from that of others whose testimony we have been recording。 In one descent； falling （without reaching earth； however） a distance of 2；130 feet in two minutes； he describes the earth rising up with frightful rapidity； though； as will be observed； this is not nearly half the speed at which either Mr。 Glaisher or Albert Smith and his companions were precipitated on to bare ground。 Very many cases which we have cited go to show that the knowledge of the great elasticity of a well…made wicker car may rob a fall otherwise alarming of its terrors； while the practical certainty that a balloon descending headlong will form itself into a natural parachute； if properly managed； reduces enormously the risk attending any mere impact with earth。 It will be allowed by all experienced aeronauts that far worse chances lie in some awkward alighting ground； or in the dragging against dangerous obstacles after the balloon has fallen。
Many of M。 Flammarion's experiments are remarkable for their simplicity。 Indeed； in some cases he would seem to have applied himself to making trials the result of which could not have been seriously questioned。 The following； quoting from Dr。 Phipson's translation； will serve as an example：
〃Another mechanical experiment was made in the evening； and renewed next day。 I wished to verify Galileo's principle of the independence of simultaneous motions。 According to this principle； a body which is allowed to fall from another body in motion participates in the motion of the latter； thus； if we drop a marble from the masthead of a ship； it preserves during its fall the rate of motion of the vessel； and falls at the foot of the mast as if the ship were still。 Now； if a body falls from a balloon； does it also follow the motion of the latter； or does it fall directly to the earth in a line which is perpendicular to the point at which we let it fall？ In the first case its fall would be described by an oblique line。 The latter was found to be the fact； as we proved by letting a bottle fall。 During its descent it partakes of the balloon's motion； and until it reaches the earth is always seen perpendicularly below the car。〃
An interesting phenomenon； relating to the formation of fog was witnessed by M。 Flammarion in one of his voyages。 He was flying low with a fast wind； and while traversing a forest he noticed here and there patches of light clouds； which； remaining motionless in defiance of the strong wind； continued to hang above the summits of the trees。 The explanation of this can hardly be doubtful； being analogous to the formation of a night…cap on a mountain peak where warm moist air…currents become chilled against the cold rock surface； forming； momentarily； a patch of cloud which； though constantly being blown away； is as constantly re…formed； and thus is made to appear as if stationary。
The above instructive phenomenon could hardly have been noticed save by an aeronaut； and the same may be said of the following。 Passing in a clear sky over the spot where the Marne flows into the Seine； M。 Flammarion notes that the water of the Marne； which； as he says； is as yellow now as it was in the time of Julius Caesar； does not mix with the green water of the Seine； which flows to the left of the current； nor with the blue water of the canal； which flows to the right。 Thus； a yellow river was seen flowing between two distinct brooks； green and blue respectively。
Here was optical evidence of the way in which streams of water which actually unite may continue to maintain independent courses。 We have seen that the same is true of streams of air； and； where these traverse one another in a copious and complex manner； we find； as will be shown； conditions produced that cause a great deadening of sound； thus； great differences in the travel of sound in the silent upper air can be noticed on different days； and； indeed； in different periods of the same aerial voyage。 M。 Flammarion bears undeniable testimony to the manner in which the equable condition of the atmosphere attending fog enhances； to the aeronaut； the hearing of sounds from below。 But when he gives definite heights as the range limits of definite sounds it must be understood that these ranges will be found to vary greatly according to circumstances。 Thus； where it is stated that a man's voice may make itself heard at 3；255 feet； it might be added that sometimes it cannot be heard at a considerably less altitude； and； again； the statement that the whistle of a locomotive rises to near 10；000 feet； and the noise of a railway train to 8；200 feet； should be qualified an additional note to the effect that both may be occasionally heard at distances vastly greater。 But perhaps the most curious observation of M。 Flammarion respecting sounds aloft relates to that of echo。 To his fancy； this had a vague depth； appearing also to rise from the horizon with a curious tone； as if it came from another world。 To the writer； on the contrary； and to many fellow observers who have specially experimented with this test of sound； the echo has always appeared to come very much from the right placethe spot nearly immediately belowand if this suggested its coming from another world then the same would have to be said of all echoes generally。
About the same period when M。 Flammarion was conducting his early ascents； MM。 de Fonvielle and Tissandier embarked on experimental voyages； which deserve some particular notice。 Interest in the new revival of the art of aeronautics was manifestly be coming reestablished in France； and though we find enthusiasts more than once bitterly complaining of the lack of financial assistance； still ballooning exhibitions； wherever accomplished； never failed to arouse popular appreciation。 But enthusiasm was by no means th
