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."