Kitabı oku: «Up in the Clouds: Balloon Voyages», sayfa 4

Chapter Six.
Ascents by Messrs Glaisher and Coxwell

We now come to that point in our subject where it is appropriate to give more detailed and graphic accounts of the recent doings of aeronauts. An extremely interesting description of a scientific balloon ascent is given by the celebrated aeronaut, Mr Glaisher, in a pamphlet, from which we shall make a few extracts.¹ His description is illustrative of the subject of ballooning, and contains the salient points of several ascents.

He asks us to imagine the balloon somewhat more than half inflated, eager for flight, with only one link connecting it with earth, namely, a rope attached to an instrument, called a liberating iron catch. When all the ballast, instruments, etcetera, were placed in the car, Mr Coxwell brought the balloon to a nice and even balance, so that the addition of twenty pounds would have prevented it from rising.

As the moment for departure drew near, friends became impatient, and every one anxiously watched the final arrangements, which were made by Mr Coxwell, on whom was laid the important duty of letting go. His hand was on the catch, his countenance was fixed, and his expression stern, as he gazed up into the heavens. He was waiting for the right moment, for the sky was partially cloudy, and it was necessary to wait until the balloon was midway between the cloud that had just passed and the next that was approaching, so that the aeronauts might have a clear sky, and be able to see the earth they were about to quit for a time. Nor was this all; he knew that in every wind, however strong it might be, there are periods of calm. If he could start in one of these he would avoid much rotatory motion. The deciding, therefore, of the exact moment for making a fair start was not so easy a matter as one might suppose.

Some one at this critical time, with the characteristic eagerness of poor human nature to “put its finger in the pie,” cried out “Now!” and another shouted “Pull!” but Mr Coxwell, regardless of every one, decided for himself; and, just when the wind lulled and the sun shone bright, and the balloon stood proudly erect, he pulled the trigger and they were free.

But they were more than free. They were suddenly in profound repose, for—however high the wind may be, however agitated the balloon, swaying to and fro with sudden and violent action, despite the efforts of many hands that endeavour to restrain it,—no sooner do aeronauts quit their hold of earth, than, in an instant, all agitation ceases and they are in perfect stillness, without any sense of motion whatever; and this freedom continues throughout the entire flight—except, indeed, when they sink so low as to come into contact with mother earth, when the serenity of their flight is terribly and violently interrupted, as shall be seen in the case of another balloon voyage hereafter to be described.

They were now fairly away, but we pause to remark, before joining them in their voyage, that their object on this occasion was not merely amusement—scientific investigation and experiment were their aim. In order that the reader may have some idea of the nature of such, we subjoin Mr Glaisher’s list of the objects of his experiments:

The primary objects were, he says, “to determine, at various heights, up to five miles—first, the pressure of the atmosphere; second, the temperature of the air; third, the hygrometrical (or moist-measured) states of the air.”

The secondary objects were:

“To compare the readings of an aneroid barometer with those of a mercurial barometer, up to five miles.

“To determine the electrical state of the air.

“To determine the oxygenic state of the atmosphere by means of ozone papers.

“To determine the time of vibration of a magnet on the earth, and at different distances from it.

“To determine the temperature of the dew point by Daniell’s dew point hygrometer and Regnault’s condensing hygrometer, and by the use of the dry and wet bulb thermometers, as ordinarily used, and their use when under the influence of the aspirator, causing considerable volumes of air to pass over both their bulbs, at different elevations, as high as possible, but particularly up to heights where man may be resident, or where troops may be located, as in the high table-lands and plains of India; with the view of ascertaining what confidence may be placed in the use of the dry and wet bulb thermometers at those elevations, by comparison with Daniell’s and Regnault’s hygrometers; and also to compare the results as found by the two hygrometers together.

“To collect air at different elevations.

“To note the height and kind of clouds, their density and thickness at different elevations.

“To determine the rate and direction of different currents in the atmosphere if possible.

“To make observations on sound.

“To note atmospherical phenomena in general, and to make general observations.”

With these objects in view the aeronauts left terra firma and soared into the skies.

“Once away,” says Mr Glaisher, “we are both immediately at work; we have no time for graceful acknowledgments to cheering friends. Mr Coxwell must put the car in order, and accordingly looks to it, to his balloon, and to the course we are taking; and I must get my instruments in order, and without delay place them in their situations, adjust them, and take a reading as soon as possible.

“In a few minutes we are from 1000 to 2000 feet high. Mr Coxwell looks intently upwards to see how the huge folds of the balloon fill into the netting. If we have started from a town, we now hear its busy hum, and the now fast fading cheers of our assembled friends naturally attract our attention. We behold at a glance the quickly-diminishing forms of the objects which we so lately left, and then resume our work.

“Presently Mr Coxwell, who is always alive to the beauties of the ever-varying scene below, and to the opening landscape, fixes his eye upon me, and, just when a rural scene of surpassing beauty is lighted up in the west, he summons me to look and admire. I struggle against picturesque temptations, somewhat at variance with my duties, but cannot so quickly suppress them. A fine cloud rears its Alpine cap in close proximity to the car; Mr Coxwell looks as delighted as an artist when he displays a magnificent painting. I feel I must conquer such enchantment, and exclaim, ‘Beautiful! grand indeed!’ and again resume my observations, with a cold philosophic resolve to pursue my readings without further interruption.

“For a while I am quiet, the instruments affording indication that we are rising rapidly. Mr Coxwell again disturbs me just as we are approaching the clouds, and recommends a farewell peep at mother earth; and just as I take this, the clouds receive us, at first in a light gauze of vapour, and then in their chilly embrace, where I examine their structure, and note the temperature of the dew point particularly.

“Shortly it becomes lighter, the light gradually increasing, till it is succeeded by a flood of light, at first striking, then dazzling, and we pass out of the dense cloud to where the clouds open out in bold and fantastic shapes, showing us light and shadow, and spectral scenes, with prismatic embellishments, disporting themselves around us in wild grandeur, till at length we break out into brilliant sunshine, and the clouds roll away in a perfect sea of vapour, obscuring the earth entirely; so that now in perfect silence I note the circumstances, and make my observations for some time uninterruptedly.

“After a time Mr Coxwell directs my attention to the fact that the balloon is full, and that the gas is coming out from the safety-valve. I of course look, for this is an exciting moment. He then directs my attention to the fit and proportions of the netting. I find the gas, which was before cloudy and opaque, is now clear and transparent, so that I can look right up the balloon and see the meshes of the net-work showing through it, the upper valve with its springs and line reaching to the car, and the geometrical form of the balloon itself. Nor is this an idle examination. I have already said that, in passing through the cloud, the netting would gather moisture, augmenting the weight of the balloon. If this should not all have evaporated, the net-work would have become frozen, and be a wire-rope; so that, if the diamond shape of the netting when under tension, and the form of the crown of the balloon, be not symmetrical, the weight might not be equally distributed, and there would be danger of it cutting the balloon. A sense of security therefore follows such an examination.

“A stream of gas now continually issues from the neck, which is very capacious, being fully two square feet in area, which is always left open. Presently I see Mr Coxwell, whose eye has been continually watching the balloon, pass his fingers over the valve-line, as if in readiness to pull the cord. I observe a slight gathering on his brow, and look inquiringly at him. He says, ‘I have decided upon opening the large upper valve,’ and carefully explains why. ‘The tension,’ he says, ‘in the balloon is not greater than it would bear with safety in a warm stratum of air; but now that we are three miles up with a chilled balloon, it is better to allow some to escape at top, as well as a good deal from the neck.’ At once I see the force of the argument, and inwardly infer that I am in no way dependent upon chance, and not likely to suffer from carelessness with Mr Coxwell. We are now far beyond all ordinary sounds from the earth; a sea of clouds is below us, so dense that it is difficult to persuade ourselves that we have passed through them. Up to this time little or no inconvenience is met with; but on passing above four miles, much personal discomfort is experienced; respiration becomes difficult; the beating of the heart at times is audible; the hands and lips become blue, and at higher elevations the face also; and it requires the exercise of a strong will to make and record observations. Before getting to our highest point, Mr Coxwell counts the number of his sandbags, and calculates how much higher we can go, with respect to the reserve of ballast necessary to regulate the descent.

“Then I feel a vibration in the car, and, on turning round, see Mr Coxwell in the act of lowering down the grapnel, then looking up at the balloon, then scanning the horizon, and weighing apparently in his mind some distant clouds through which we are likely to pass in going down.

“A glance suffices to show that his mind is made up how much higher it is prudent to rise, and how much ballast it is expedient to preserve.

“The balloon is now lingering, as it were, under the deep blue vault of space, hesitating whether to mount higher or begin its descent without further warning. We now hold a consultation, and then look around from the highest point, giving silent scope to those emotions of the soul which are naturally called forth by such a wide-spread range of creation.

“Our course is now about to change. But here I interpose with ‘No, no; stop; not yet; let us remain so long that the instruments are certain to take up the true temperature, and that no doubt can rest upon the observations here. When I am satisfied I shall say, “Pull.”’

“Then in silence—for here we respire with difficulty, and talk but little—in the centre of this immense space, in solitude, without a single object to interrupt the view for 200 miles or more all round, abstracted from the earth, upheld by an invisible medium, our mouths so dry that we cannot eat, a white sea below us, so far below, we see few, if any, irregularities. I watch the instruments; but, forcibly impelled, again look round from the centre of this vacuity, whose boundary-line is 1500 miles, commanding nearly 130,000 square miles, till I catch Mr Coxwell’s eye turned towards me, when I again direct mine to the instruments; and when I find no further changes are proceeding, I wave my hand and say, ‘Pull.’

“A deep resonant sound is heard overhead; a second pull is followed by a second report, that rings as with shrill accompaniment down the very sides of the balloon. It is the working of the valve, which causes a loud booming noise, as from a sounding-board, as the springs force the shutters back.

“But this sound in that solitary region, amid silence so profound that no silence on earth is equal to it,—a drum-like sound meeting the ear from above, from whence we do not usually hear sounds—strikes one forcibly. It is, however, one sound only; there is no reverberation, no reflection; and this is characteristic of all sounds in the balloon,—one clear sound continuing during its vibrations, then gone in a moment. No sound ever reaches the ear a second time. But though the sound from the closing of the valve in those silent regions is striking, it is also cheering,—it is reassuring; it proves all to be right, that the balloon is sound, that the colder regions have not frozen tight the outlet for gas, and that we are so far safe. We have descended a mile, and our feelings improve with the increase of air and warmth. But silence reigns supreme, and Mr Coxwell, I observe, turns his back upon me, scanning intently the cloudscape, speculating as to when and where we shall break through and catch sight of the earth. We have been now two hours without seeing terra firma. How striking and impressive is it to realise a position such as this; and yet as men of action, whose province it is to subordinate mere feelings, we refrain from indulging in sentiment. I say refrain, for presently Mr Coxwell breaks out, no longer able to contain himself: ‘Here, Mr Glaisher, you must welcome another balloon. It is the counterpart of our own.’ This spectral balloon is charming to look upon, and presents itself under a variety of imposing aspects, which are magnified or diminished by the relative distance of our balloon from the clouds, and by its position in relation to the sun, which produces the shadow. At mid-day it is deep down, almost underneath; but it is more grandly defined towards evening, when the golden and ruby tints of the declining sun impart a gorgeous colouring to cloudland. You may then see the spectre balloon magnified upon the distant cloud-tops, with three beautiful circles of rainbow tints. Language fails utterly to describe these illuminated photographs, which spring up with matchless truthfulness and choice decoration.

“Just before we enter the clouds, Mr Coxwell, having made all preparations for the descent, strictly enjoins me to be ready to put up the instruments, lest, when we lose the powerful rays of the sun, and absorb the moisture of the lower clouds, we should approach the earth with too great rapidity.

“We now near the confines of the clouds, and dip swiftly into the thickest of them; we experience a decided chill, and hear the rustling of the collapsing balloon, which is now but one-third full, but cannot see it, so dense is the mass of vapour. One, two, three, or more minutes pass, and we are still in the cloud. How thick it must be, considering the rapidity of the descent! Presently we pass below, and the earth is visible. There is a high road intersecting green pastures; a piece of water looking like polished steel presents itself; a farmhouse, with stacks and cattle, is directly under us. We see the sea-coast, but at a distance. An open country lies before us. A shout comes up, and announces that we are seen, and all goes well, save the rapidity of our descent, which has been caused by that dark frowning cloud which shut us out from the sun’s rays, and bedewed us with moisture. Mr Coxwell, however, is counteracting it by means of the ballast, and streams out one bag, which appears to fly up instead of falling down; now another is cast forth, but still it goes up, up. A third reduces the wayward balloon within the bounds of moderation, and Mr Coxwell exultingly exclaims that ‘he has it now under perfect command, with sand enough, and to spare.’

“Delighted to find the balloon is thus checked, as it is favourable to good readings of the several instruments at this elevation, I work as quickly as I can, noticing also the landscape below; rich mounds of green foliage, fields of various shades of green, like a tessellated pavement in motion; with roads, rivers, rivulets, and the undulatory nature of the ground varying the scene every instant. Should our passage be over a town, it is like a model in motion; and all is seen with a distinctness superior to that from the earth; the line of sight is through a purer and less dense medium; everything seems clearer, though smaller; even at the height of four miles above Birmingham we distinguished the New Street Station and the streets.

“We have been descending slowly for a little time, when I am challenged to signify when I can close my observations, as yonder, about two miles distant, is a fine park, where Mr Coxwell’s eye seems to wander with something like a desire to enter it. I approve of the spot, as it is in every way suitable for a descent. The under-current, which is oftentimes stronger than the upper, is wafting us merrily in that direction. We are now only a few hundred feet above the surface. ‘Put up your instruments,’ cries Mr Coxwell, ‘and we will keep on this level until you are ready.’

“A little more sand is let out, and I pack up the instruments quickly in their wadded cases. ‘Are you all right?’ inquires the aeronaut. ‘All right,’ I respond; ‘look out then, and hold fast by the ropes, as the grapnel will stop us in that large meadow, with the hedgerow in front.’

“There, sure enough, we land. The cattle stand at bay affrighted, their tails are horizontal, and they run wildly away. But a group of friends from among the gentry and villagers draws up near the balloon, and although some few question whether we belong to this planet, or whether we are just imported from another, yet any doubt upon this point is soon set at rest, and we are greeted with a hearty welcome from all when we tell our story, how we travelled the realms of space, not from motives of curiosity, but for the advancement of science, its applicability to useful purposes, and the good of mankind.”

In commenting on the several ascents thus combined in one description, Mr Glaisher gives us various pieces of information which are highly interesting. The clouds, he says, on which the sun was shining brightly, each moment opened up to view deep ravines, and shining masses appeared like mountain ranges, some rising perpendicularly from rolling seas or plains, with summits of dazzling brightness, some pyramidal, others undulatory, with deep shadows between.

While passing over London on one occasion at night, at the height of about one mile, he heard the hum of the great city, and saw its lights. The river looked dull, but the bridges that spanned it, and the many miles of straight, intersecting, and winding streets were distinctly visible.

In referring to sound, he tells us that, on different occasions, at a height of 11,800 feet above the earth, a band was heard playing. At between four and five thousand feet a railway whistle and the shouting of people were heard, and at 10,070 feet the report of a gun. A dog was also heard barking at a height of two miles. At a height of 19,000 feet the hands and lips were observed, during one ascent, to be of a dark bluish colour. At four miles the palpitations of the heart were audible, and the breathing was affected. Considerable difficulty was experienced in respiration at higher elevations. From his various observations he found that the effect of high elevation is different upon the same individuals at different times, and believed that, up to heights less than three miles—to which persons of ordinary self-possession might ascend—delicate and accurate scientific observations might be made with ease, but at heights approaching to four miles, such observations could not be made so well, because of the personal distress of the observer, and on approaching to five miles above the earth it required the exercise of a strong will to take any observations at all.

The most wonderful and alarming of the experiences of Mr Glaisher appear to have occurred to him and his companion, Mr Coxwell, during an ascent made from Wolverhampton on the 5th September, when they reached the enormous elevation of between six and seven miles.

They felt no particular inconvenience until after passing above the fifth mile. When at a height of 26,000 feet, Mr Glaisher could not see the column of mercury in the tube; then the fine divisions on the scale of the instrument became invisible. Shortly afterwards he laid his arm on the table, and on attempting again to use it found that the limb was powerless. He tried to move the other arm, and found that it also was paralysed. He then tried to shake himself, and succeeded in shaking his body, but experienced the curious sensation of having no legs! While in this condition he attempted to look at the barometer, and, while doing so, his head fell on his left shoulder. Struggling to get out of this lethargic state, he found that he could still shake his body, although he could not move either arms or legs. He got his head upright for an instant, but it dropped again on his shoulder, and he fell backwards, his back resting against the side of the car, and his head on its edge.

In this position his eyes were directed to Mr Coxwell, who did not at first observe the state of his companion, in consequence of his having had to ascend into the ring of the balloon to disentangle the valve-line, which had become twisted. Hitherto Mr Glaisher had retained the power of moving the muscles of his back and neck, but suddenly this was lost to him. He saw Mr Coxwell dimly in the ring, and attempted to speak to him, but could not do so. A moment later intense black darkness surrounded him—the optic nerve had lost its power! He was still conscious, however, and with his brain as active as at other times. He fancied he had been seized with asphyxia, and that death would quickly ensue unless they descended without delay. Suddenly the power of thought ceased, and he became unconscious. All these extraordinary and alarming sensations, he calculated, must have taken place within five or six minutes.

While still powerless he heard the words “temperature” and “observation,” and knew that Mr Coxwell was in the car endeavouring to arouse him. Presently he heard him speak more emphatically, but could neither see, reply, nor move. Then he heard him say, “Do try now, do,” after which vision slightly returned, and in a short time he saw clearly again, rose from his seat, looked round, and said to Mr Coxwell, “I have been insensible.” His friend replied, “You have, and I too very nearly.” Mr Coxwell had lost the use of his hands, which were black; Mr Glaisher, therefore, poured brandy over them. His companion then told him that, on descending from the ring, he thought he had laid himself back to rest, but noticing that his legs projected, and his arms hung down by his side, it struck him there was something wrong, and he attempted to go to his assistance, but felt insensibility coming over himself. He tried to open the valve, so that they might descend, but, having lost the use of his hands, could not. In this critical moment he seized the cord with his teeth, dipped his head two or three times, and thus succeeded in opening the valve and descending from those dangerous regions of attenuated atmosphere!

At first they went down at the tremendous rate of twenty miles an hour, but after descending three miles in nine minutes, the balloon’s progress was checked, and they finally alighted safely in a grass field, where their appearance so terrified the country folk that it required a good deal of coaxing in plain English to convince them that the aeronauts were not inhabitants of another world!