By this period a revival of aeronautics in the land of its birth had fairly set in. Since the last ascents of Gay Lussac, in 1804, already recorded, there had been a lull in ballooning enterprise in France, and no serious scientific expeditions are recorded until the year 1850, when MM. Baral and Bixio undertook some investigations respecting the upper air, which were to deal with its laws of temperature and humidity, with the proportion of carbonic acid present in it, with solar heat at different altitudes, with radiation and the polarisation of light, and certain other interesting enquiries.

The first ascent, made in June from the Paris Observatory, though a lofty one, was attended with so much danger and confusion as to be barren of results. The departure, owing to stormy weather, was hurried and illordered, so that the velocity in rising was excessive, the net constricted the rapidly-swelling globe, and the volumes of out-rushing gas half-suffocated the voyagers. Then a large rent occurred, which caused an alarmingly rapid fall, and the two philosophers were reduced to the necessity of flinging away all they possessed, their instruments only excepted. The landing, in a vineyard, was happily not attended with disaster, and within a month the same two colleagues attempted a second aerial excursion, again in wet weather.

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 place - the spot nearly immediately below - and 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 the universal attitude with which the world regarded aerial enterprise. A remarkable and instructive instance is given to the contrary by M. W. de Fonvielle himself.

He records an original ballooning exploit, organised at Algiers, which one might have supposed would have caused a great sensation, and to which he himself had called public attention in the local journals. The brothers Braguet were to make an ascent from the Mustapha Plain in a small fire balloon heated with burning straw, and this risky performance was successfully carried out by the enterprising aeronauts. But, to the onlooker, the most striking feature of the proceeding was the fact that while the Europeans present regarded the spectacle with curiosity and pleasure, the native Mussulmans did not appear to take the slightest interest in it; "And this," remarked de Fonvielle, "was not the first time that ignorant and fanatic people have been noted as manifesting complete indifference to balloon ascents. After the taking of Cairo, when General Buonaparte wished to produce an effect upon the inhabitants, he not only made them a speech, but supplemented it with the ascent of a fire balloon. The attempt was a complete failure, for the French alone looked up to the clouds to see what became of the balloon."

In the summer of 1867 an attempt was made to revive the long extinct Aeronautic Company of France, established by De Guyton. The undertaking was worked with considerable energy. Some forty or fifty active recruits were pressed into the service, a suitable captive balloon was obtained, thousands of spectators came to watch the evolutions; and many were found to pay the handsome fee of 100 francs for a short excursion in the air. For all this, the effort was entirely abortive, and the ballooning corps, as such, dropped out of existence.

A little while after this de Fonvielle, on a visit to England, had a most pathetic interview with the veteran Charles Green, who was living in comfortable retirement at Upper Holloway. The grand old man pointed to a well-filled portfolio in the corner of his room, in which, he said, were accounts of all his travels, that would require a lifetime to peruse and put in order. Green then took his visitor to the end of the narrow court, and, opening the door of an outhouse, showed him the old Nassau balloon. "Here is my car," he said, touching it with a kind of solemn respect, "which, like its old pilot, now reposes quietly after a long and active career. Here is the guide rope which I imagined in former years, and which has been found very useful to aeronauts.... Now my life has past and my time has gone by.... Though my hair is white and my body too weak to help you, I can still give you my advice, and you have my hearty wishes for your future."

It was but shortly after this, on March 26, 1870, that Charles Green passed away in the 85th year of his age.

De Fonvielle's colleague, M. Gaston Tissandier, was on one occasion accidentally brought to visit the resting place of the earliest among aeronauts, whose tragic death occurred while Charles Green himself was yet a boy. In a stormy and hazardous descent Tissandier, under the guidance of M. Duruof, landed with difficulty on the sea coast of France, when one of the first to render help was a lightkeeper of the Griz-nez lighthouse, who gave the information that on the other side of the hills, a few hundred yards from the spot where they had landed, was the tomb of Pilatre de Rozier, whose tragical death has been recorded in an early chapter. A visit to the actual locality the next day revealed the fact that a humble stone still marked the spot.

Certain scientific facts and memoranda collected by the talented French aeronaut whom we are following are too interesting to be omitted. In the same journey to which we have just referred the voyagers, when nearly over Calais, were witnesses from their commanding standpoint of a very striking phenomenon of mirage. Looking in the direction of England, the far coast line was hidden by an immense veil of leaden-coloured cloud, and, following this cloud wall upward to detect where it terminated, the travellers saw above it a greenish layer like that of the surface of the sea, on which was detected a little black point suggesting a walnut shell. Fixing their eyes on this black spot, they presently discerned it to be a ship sailing upside down upon an aerial ocean. Soon after, a steamer blowing smoke, and then other vessels, added themselves to the illusory spectacle.

Another wonder detected, equally striking though less uncommon, was of an acoustical nature, the locality this time being over Paris. The height of the balloon at this moment was not great, and, moreover, was diminishing as it settled down. Suddenly there broke in upon the voyagers a sound as of a confused kind of murmur. It was not unlike the distant breaking of waves against a sandy coast, and scarcely less monotonous. It was the noise of Paris that reached them, as soon as they sank to within 2,600 feet of the ground, but it disappeared at once when they threw out just sufficient ballast to rise above that altitude.

It might appear to many that so strange and sudden a shutting out of a vast sound occurring abruptly in the free upper air must have been more imaginary than real, yet the phenomenon is almost precisely similar to one coming within the experience the writer, and vouched for by his son and daughter, as also by Mr. Percival Spencer, all of whom were joint observers at the time, the main point of difference in the two cases being the fact that the "region of silence" was recorded by the French observers as occurring at a somewhat lower level. In both cases there is little doubt that the phenomenon can be referred to a stratum of disturbed or non-homogeneous air, which may have been very far spread, and which is capable of acting as a most opaque sound barrier.

Attention has often been called in these pages to the fact that the action of the sun on an inflated balloon, even when the solar rays may be partially obscured and only operative for a few passing moments, is to give sudden and great buoyancy to the balloon. An admirable opportunity for fairly estimating the dynamic effect of the sun's rays on a silk globe, whose fabric was half translucent, was offered to the French aeronauts when their balloon was spread on the grass under repair, and for this purpose inflated with the circumambient air by means of a simple rotatory fan. The sun coming out, the interior of the globe quickly became suffocating, and it was found that, while the external temperature recorded 77 degrees, that of the interior was in excess of 91 degrees.