Full details have been given in this chapter of the monster balloon constructed by M. Nadar; but in 1864 Eugene Godard built one larger yet of the Montgolfier type. Its capacity was nearly half a million cubic feet, while the stove which inflated it stood 18 feet high, and weighed nearly 1,000 pounds. Two free ascents were made without mishap from Cremorne Gardens. Five years later Ashburnham Park was the scene of captive ascents made with another mammoth balloon, containing no less than 350,000 cubic feet of pure hydrogen, and capable of lifting 11 tons. It was built at a cost of 28,000 francs by M. Giffard, the well-known engineer and inventor of the injector for feeding steam engines. These aerial leviathans do not appear to have been, in any true sense successful. CHAPTER XVIII. THE BALLOON IN THE SIEGE OF PARIS. 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.