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.