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.