Up in the Clouds: Balloon Voyages, R. M. Ballantyne [top e book reader .txt] 📗

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. (See Note 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