Within a few months of the completion of the period covered by the records of the last chapter, France was destined to receive a more urgent stimulus than ever before to develop the resources of ballooning, and, in hot haste, to turn to the most serious and practical account all the best resources of aerial locomotion. The stern necessity of war was upon her, and during four months the sole mode of exit from Paris - nay, the only possible means of conveying a simple message beyond the boundary of her fortifications - was by balloon.

Hitherto, from the very inception of the art from the earliest Montgolfier with its blazing furnace, the balloon had gone up from the gay capital under every variety of circumstance - for pleasure, for exhibition, for scientific research. It was now put in requisition to mitigate the emergency occasioned by the long and close investment of the city by the Prussian forces.

Recognising, at an early stage, the possibilities of the balloon, an enquiry was at once made by the military authorities as to the existing resources of the city, when it was quickly discovered that, with certain exceptions to be presently mentioned, such balloons as were in existence within the walls were either unserviceable or inadequate for the work that was demanded of them. Thereupon, with admirable promptness and enterprise, it was forthwith determined to organise the building and equipment of a regular fleet of balloons of sufficient size and strength.

It chanced that there were in Paris at the time two professional aeronauts of proved experience and skill, both of whom had become well known in London only the season before in connection with M. Giffard's huge captive balloon at Ashburnham Park. These were MM. Godard and Yon, and to them was entrusted the establishment of two separate factories in spacious buildings, which were at once available and admirably adapted for the purpose. These were at the Orleans and the Northern Railway stations respectively, where spacious roofs and abundant elbow room, the chief requisites, were to be found. The first-mentioned station was presided over Godard, the latter by M. Yon, assisted by M. Dartois.

It was not doubted that the resources of the city would be able to supply the large demand that would be made for suitable material; but silk as a fabric was at once barred on the score of expense alone. A single journey was all that needed to be calculated on for each craft, and thus calico would serve the purpose, and would admit of speedy making up. Slight differences in manufacture were adopted at the two factories. At the Northern station plain white calico was used, sewn with a sewing machine, whereas at the Orleans station the material was coloured and entrusted only to hand stitching. The allimportant detail of varnish was supplied by a mixture of linseed oil and the active principle of ordinary driers, and this, laid on with a rubber, rendered the material gas-tight and quickly dry enough for use. Hundreds of hands, men and women, were employed at the two factories, at which some sixty balloons were produced before the end of the siege. Much of the more important work was entrusted to sailors, who showed special aptness, not only in fitting out and rigging the balloons, but also in their management when entrusted to the winds.

It must have been an impressive sight for friend or foe to witness the departure of each aerial vessel on its venturesome mission. The bold plunge into space above the roofs of the imprisoned city; the rapid climb into the sky and, later, the pearl drop high in air floating away to its uncertain and hazardous haven, running the gauntlet of the enemy's fire by day or braving what at first appeared to be equal danger, attending the darkness of night. It will be seen, however, that, of the two evils, that of the darkness was considered the less, even though, with strange and unreasonable excess of caution, the aeronauts would not suffer the use of the perfectly safe and almost indispensable Davy lamp.

Before any free ascents were ventured on, two old balloons were put to some practical trial as stationary observatories. One of these was moored at Montmartre, the other at Mont-souris. From these centres daily, when the weather permitted, captive ascents were made - four by day and two by night - to watch and locate the movements of the enemy. The system, as far as it went, was well planned. It was safe, and, to favour expedition, messages were written in the car of the balloon and slid down the cable to the attendants below. The net result, however, from a strategic point of view, does not appear to have been of great value.

Ere yet the balloons were ready, certain bold and eventful escapes were ventured on. M. Duruof, already introduced in these pages, trusting himself to the old craft, "Le Neptune," in unskyworthy condition, made a fast plunge into space, and, catching the upper winds, was borne away for as long a period as could be maintained at the cost of a prodigal expenditure of ballast. The balloon is said to have described a visible parabola, like the trajectory of a projectile, and fell at Evreux in safety and beyond the range of the enemy's fire, though not far from their lines. This was on the 23rd of September. Two days afterwards the first practical trial was made with homing pigeons, with the idea of using them in connection with balloons for the establishment of an officially sanctioned post. MM. Maugin and Grandchamp conducted this voyage in the "Ville de Florence," and descended near Vernouillet, not far beyond Le Foret de St. Germain, and less than twenty miles from Paris. The serviceability of the pigeon, however, was clearly established, and a note contributed by Mr. Glaisher, relating to the breeding and choice of these birds, may be considered of interest. Mr. R. W. Aldridge, of Charlton, as quoted by Mr. Glaisher, stated that his experience went to show that these birds can be produced with different powers of orientation to meet the requirements of particular cases. "The bird required to make journeys under fifty miles would materially differ in its pedigree from one capable of flying 100 or 600 miles. Attention, in particular, must be given to the colour of the eye; if wanted for broad daylight the bird known as the 'Pearl Eye,' from its colour, should be selected; but if for foggy weather or for twilight flying the black- or blue-eyed bird should receive the preference."

Only a small minority, amounting to about sixty out of 360 birds taken up, returned to Paris, but these are calculated to have conveyed among them some 100,000 messages. To reduce these pigeon messages to the smallest possible compass a method of reduction by photography was employed with much success. A long letter might, in this way, be faithfully recorded on a surface of thinnest photographic paper, not exceeding the dimensions of a postage stamp, and, when received, no more was necessary than to subject it to magnification, and then to transcribe it and send a fair copy to the addressee.

The third voyage from Paris, on September 29th was undertaken by Louis Godard in two small balloons, united together, carrying both despatches and pigeons, and a safe landing was effected at Mantes This successful feat was rival led the next day by M. Tissandier, who ascended alone in a balloon of only some 26,000 cubic feet capacity and reached earth at Dreux, in Normandy.

These voyages exhausted the store of ready-made balloons, but by a week later the first of those being specially manufactured was ready, and conveyed in safety from the city no less a personage than M. Gambetta.

The courageous resolve of the great man caused much sensation in Paris, the more so because, owing to contrary winds, the departure had to be postponed from day to day. And when, at length, on October 7th, Gambetta and his secretary, with the aeronaut Trichet, actually got away, in company with another balloon, they were vigorously fired at with shot and shell before they had cleared St. Denis. Farther out over the German posts they were again under fire, and escaped by discharging ballast, not, however, before Gambetta had been grazed by a bullet. Yet once more they were assailed by German volleys before, about 3 p.m., they found a haven near Montdidier.

The usual dimensions of the new balloons gave a capacity of 70,000 cubic feet, and each of these, when inflated with coal gas, was calculated to convey a freight of passengers, ballast, and despatches amounting to some 2,000 pounds. Their despatch became frequent, sometimes two in the same twenty-four hours. In less than a single week in October as many as four balloons had fallen in Belgium, and as many more elsewhere. Up till now some sixteen ventures had ended well, but presently there came trouble. On October 22nd MM. Iglesia and Jouvencel fell at Meaux, occupied by the Prussians; their despatches, however, were saved in a dung cart. The twenty-third voyage ended more unhappily. On this occasion a sailor acted as aeronaut, accompanied by an engineer, Etienne Antonin, and carrying nearly 1,000 pounds of letters. It chanced that they descended near Orleans on the very day when that town was re-occupied by the enemy, and both voyagers were made prisoners. The engineer, however, subsequently escaped. Three days later another sailor, also accompanied by an engineer, fell at the town of Ferrieres, then occupied by the Prussians, when both were made prisoners. In this case, also, the engineer succeeded in making his escape; while the despatches were rescued by a forester and forwarded in safety.

At about this date W. de Fonvielle, acting as aeronaut, and taking passengers, made a successful escape, of which he has given a graphic account. He had been baulked by more than one serious contretemps. It had been determined that the departure should be by night, and November 19th being fixed upon, the balloon was in process of inflation under a gentle wind that threatened a travel towards Prussian soil, when, as the moment of departure approached, a large hole was accidentally made in the fabric by the end of the metal pipe, and it was then too late to effect repairs. The next and following days the weather was foul, and the departure was not effected till the 25th, when he sailed away over the familiar but desolated country. He and his companions were fired at, but only when they were well beyond range, and in less than two hours the party reached Louvain, beyond Brussels, some 180 English miles in a direct line from their starting point. This was the day after the "Ville d'Orleans" balloon had made the record voyage and distance of all the siege, falling in Norway, 600 miles north of Christiania, after a flight of fifteen hours.

At the end of November, when over thirty escape voyages had been made, two fatal disasters occurred. A sailor of the name of Prince ascended alone on a moonless night, and at dawn, away on the north coast of Scotland, some fishermen sighted a balloon in the sky dropping to the westward in the ocean. The only subsequent trace of this balloon was a bag of despatches picked up in the Channel. Curiously enough, two days later almost the same story was repeated. Two aeronauts, this time in charge of despatches and pigeons, were carried out to sea and never traced.

Undeterred by these disasters, a notable escape was now attempted. An important total eclipse of the sun was to occur in a track crossing southern Spain and Algeria on December 22nd. An enthusiastic astronomer, Janssen, was commissioned by the Academy of Sciences to attend and make observations of this eclipse. But M. Janssen was in Paris, as were also his instruments, and the eclipse track lay nearly a thousand miles away. The one and only possible mode of fulfilling his commission was to try the off-chance afforded by balloon, and this chance he resorted to only twenty days before the eclipse was due.

Taking with him the essential parts of a reflecting telescope, and an active young sailor as assistant, he left Paris at 6 a.m. and rose at once to 3,600 feet, dipping again somewhat at sunrise (owing, as he supposed, to loss of heat through radiation), but subsequently ascending again rapidly under the increased altitude of the sun till his balloon attained its highest level of 7,200 feet. From this elevation, shortly after 11 a.m., he sighted the sea, when he commenced a descent which brought him to earth at the mouth of the Loire. It had been fast travelling - some 300 miles in little more than three hours - and the ground wind was strong. Nevertheless, neither passengers nor instruments were injured, and M. Janssen was fully established by the day of eclipse on his observing ground at Oran, on the Algerian coast. It is distressing to add that the phenomenon was hidden by cloud. In the month that followed this splendid venture no fewer than fifteen balloons escaped from Paris, of which four fell into the hands of the enemy, although for greater security all ascents were now being made by night.

On January 13th, 1871, a new device for the return post was tried, and, in addition to pigeons, sheep dogs were taken up, with the idea of their being returned to the city with messages concealed within their collars. There is apparently no record of any message having been returned to the town by this ingenious method. On January 24th a balloon, piloted by a sailor, and containing a large freight of letters, fell within the Prussian lines, but the patriotism of the country was strong enough to secure the despatches being saved and entrusted to the safe conveyance of the Post Office. Then followed the total loss of a balloon at sea; but this was destined to be the last, save one, that was to attempt the dangerous mission. The next day, January 28th, the last official balloon left the town, manned by a single sailor, carrying but a small weight of despatches, but ordering the ships to proceed to Dieppe for the revictualling of Paris.

Five additional balloons at that time in readiness were never required for the risky service for which they were designed.

There can be little doubt that had the siege continued a more elaborate use of balloons would have been developed. Schemes were being mooted to attempt the vastly more difficult task of conveying balloons into Paris from outside. When hostilities terminated there were actually six balloons in readiness for this venture at Lisle, and waiting only for a northerly wind. M. de Fonvielle, possessed of both courage and experience, was prepared to put in practice a method of guiding by a small propelling force a balloon that was being carried by sufficiently favouring winds within a few degrees of its desired goal - and in the case of Paris the goal was an area of some twenty miles in diameter. Within the invested area several attempts were actually made to control balloons by methods of steering. The names of Vert and Dupuy de Lome must here be specially mentioned. The former had elaborated an invention which received much assistance, and was subsequently exhibited at the Crystal Palace. The latter received a grant of L1,600 to perfect a complex machine, having within its gas envelope an air chamber, suggested by the swimming bladder of a fish, having also a sail helm and a propelling screw, to be operated by manual labour.

The relation of this invention to others of similar purpose will be further discussed later on. But an actual trial of a dirigible craft, the design of Admiral Labrousse, was made from the Orleans railway station on January 9th. This machine consisted of a balloon of about the standard capacity of the siege balloons, namely some 70,000 cubic feet, fitted with two screws of about 12 feet diameter, but capable of being readily worked at moderate speed. It was not a success. M. Richard, with three sailors, made a tentative ascent, and used their best endeavours to control their vessel, but practically without avail, and the machine presently coming to earth clumsily, a portion of the gear caught in the ground and the travellers were thrown over and roughly dragged for a long distance.

Fairly looked at, the aerial post of the siege of Paris must be regarded as an ambitious and, on the whole, successful enterprise. Some two million and a half of letters, amounting in weight to some ten tons, were conveyed through the four months, in addition to which at least an equal weight of other freight was taken up, exclusive of actual passengers, of whom no fewer than two hundred were transported from the beleaguered city. Of these only one returned, seven or eight were drowned, twice this number were taken prisoners, and as many again more or less injured in descents. From a purely financial point of view the undertaking was no failure, as the cost, great as it necessarily became, was, it is said, fairly covered by the postage, which it was possible and by no means unreasonable to levy. The recognised tariff seems to have been 20 centimes for 4 grammes, or at the rate of not greatly more than a shilling per English ounce. Surely hardly on a par with famein prices in a time of siege.

It has already been stated that the defenders of Paris did not derive substantial assistance from the services of such a reconnoitring balloon as is generally used in warfare at every available opportunity. It is possible that the peculiar circumstances of the investment of the town rendered such reconnaissance of comparatively small value. But, at any rate, it seems clear that due opportunity was not given to this strategic method. M. Giffard, who at the commencement of the siege was in Paris, and whose experience with a captive balloon was second to none, made early overtures to the Government, offering to build for L40,000 a suitable balloon, capable of raising forty persons to a heightm of 3,000 feet. Forty aerial scouts, it may be said, are hardly needed for purposes of outlook at one time; but it appears that this was not the consideration which stood in the way of M. Giffard's offer being accepted. According to M. de Fonvielle, the Government refused the experienced aeronaut's proposal on the ground that he required a place in the Champs Elysees, "which it would be necessary to clear of a few shrubs"!