Gye & Hughes, the proprietors of Vauxhall Gardens, ascended from them with Mr. Green, Mr. Edward Spencer, and Mr. Rush of Elsenham Hall, Essex, the latter gentleman having engaged the balloon for experimental purposes, and more particularly on this occasion for ascertaining the greatest altitude that could with safety be attained with three persons in the car; and further to ascertain the changes of temperature that would take place at different elevations, as well as the variations of the currents of air; and finally, to establish the important fact, as to whether the same difficulties with regard to respiration in a very rarified atmosphere would be experienced by persons rising in a balloon to any great altitude, as have been felt by persons who have ascended lofty mountains, and by previous aërial travellers in balloons to great heights.

They left the earth at twenty-five minutes before 7 p.m. with two barometers standing at thirty inches each.

One of these instruments, as well as a thermometer, was furnished by Mr. Rush, constructed on the most accurate principles, and made expressly for the purpose. The thermometer stood at 66 Fahrenheit.

The following were the variations:

On first rising they took a north-westerly direction; at 2,500 it changed to the north, and shortly afterwards to north-east.

Their journey was pursued towards Epping, and they were discharging ballast all the time. Leaving Dunmow to their left they attained their greatest altitude, namely, 19,335 feet, or three and a half miles and 855 feet.

In consequence of the great quantity of sand discharged after clearing the Metropolis their ascent became very rapid, and, from the great expansion of the inflating power, the gas rushed out from the lower valve in considerable torrents.

The velocity of their upward progress caused the balloon to rotate in a spiral motion with astonishing. rapidity.

During their trip about 1,200 pounds of ballast was discharged, but they reserved 100 pounds by which to regulate the descent.

During their descent, when at 1,200 feet from the earth, a heavy fall of snow was encountered, accompanied by a sudden and very great reduction of temperature, the thermometer dropping to 22°, or 10° below freezing point. The mercury in the barometer at this moment had risen to nineteen inches.

I mention this circumstance for the purpose of showing that sometimes sudden changes of temperature have been experienced, not only by Green, but by Bixio and Barral later on in the present century.

The fatigue of the muscular powers, occasioned by

exertion in emptying ballast, did not occasion any serious inconvenience in respect to difficulty in respiration.

We shall see, in the next ascent which was still higher, that the plan I have already exemplified as to allowing considerable space for expansion was resorted to, and this saved both the necessity for and the depression consequent upon hard work, although a large volume of gas was literally wasted, which might, in an economical point of view, have been prevented; but it will serve to show that a large balloon partially inflated, with a reduced amount of sand, is for all practical and scientific purposes preferable to a fully inflated balloon, that is, for very high ascents.

The ordinary way of examining the specific gravity of the different gases is by a simple method founded on the principles of pneumatics, for discovering the relative specific gravities of the aëriform fluids.

This consists in observing the time that a given portion of the gas, under a determined pressure, takes to escape through a very small aperture. The density of the gaseous fluid must be inversely as the square of the interval that elapses.

The weight of the balloon and all appendages must evidently compress the included gas, and thereby render it in some degree denser.

To compute this minute effect, we have only to consider that the pressure of a column of atmosphere at the mean temperature, and near the level of the sea, is 1632 pounds on a circle of a foot in diameter.

Thus, in a balloon of sixty feet in diameter, if we suppose the whole load to have been 6000 pounds, the compression

of the bag would only amount to five-thirds of a pound for each circle of a foot in diameter in the horizontal action, or corresponding to the 979th part of the entire pressure of the atmosphere.

But the weight of the confined gas (hydrogen) being 1200 pounds, its buoyancy must have suffered a diminution of somewhat more than a pound or one-eleventh from the circumference opposed to it.

But as I have purposely abstained from giving in this first elementary part any computations of an abstruse order by more learned and capable writers than myself, I shall reserve further remarks on this particular head for my subsequent volume.

ASCENT, OVER FIVE MILES HIGH, BY GREEN AND RUSH.

I have before me a mass of leading articles and newspaper cuttings alluding to the ascent of Messrs. Jovis and Mallet, in which honourable mention is made of the lofty explorations by Robertson and L'Hoest, Gay-Lussac, Bixio, and Barral, together with Mr. Glaisher's and my own, but Green's with Rush are invariably omitted, and yet these were quite as important, while the second was higher than that made by the intrepid French balloonists, and, so far as physicial results go, the Englishmen do not appear to have fainted or been much troubled.

It is of immense importance to note this, as there can be no doubt that a certain zone exists, in entering which some persons are more susceptible than others to lessened atmospheric pressure, and here they begin to feel the bad

effects, which, by the way may come on without warning, just as it is with Alpine travellers, although there are marked distinctions between the two, but we cannot enter upon that in detail in this chapter.

This trip, by Green, was one of those which was designed to add a fraction of knowledge to the already existing stores of science. This fact is sufficient, even according to those who are not great admirers of ballooning, to warrant its encouragement when taken in hand by those who do not affect to be mere aëronautic performers, embarking in aërostatic pursuits for sensational objects, or with the vain and delusive idea, that it is not dangerous, and that it is a money-making

concern.

Mr. Rush, assisted by the knowledge of his coadjutor, threw a character of deep interest over the whole subject of aërostation, and this trip, though lost sight of, at the present moment, is well worthy of re-production, serving as it does, two ends; firstly, to call attention to the fact, that English aëronauts seem to get more toughened by acclimatization to rarified air than Frenchmen, and secondly, that they do such work with less ado, and with equal, perhaps a little more, methodical foresight and precision, than our more dashing and mercurial neighbours.

It was on the 10th of September (what a number of exceptionable journeys were made in this month!) that the highest ascent which had been made up to that date, came off from the far-famed Vauxhall Gardens.

The proprietors made arrangements with Mr. Rush for