It was now that the practice of ballooning became a recognised department of military manoeuvres, and a valuable report appears in the above-mentioned papers from the pen of Captain F. Beaumont, R.E. According to this officer, the Americans made trial of two different balloons, both hydrogen inflated, one having a capacity of about 13,000 cubic feet, and the other about twice as large. It was this latter that the Americans used almost exclusively, it being found to afford more steadiness and safety, and to be the means, sometimes desirable, of taking up more than two persons. The difficulty of sufficient gas supply seems to have been well met. Two generators sufficed, these being "nothing more than large tanks of wood, acid-proof inside, and of sufficient strength to resist the expansive action of the gas; they were provided with suitable stopcocks for regulating the admission of the gas, and with manhole covers for introducing the necessary materials." The gas, as evolved, being made to pass successively through two vessels containing lime water, was delivered cool and purified into the balloon, and as the sulphuric acid needed for the process was found sufficiently cheap, and scrap iron also required was readily come by, it would seem that practical difficulties in the field were reduced to a minimum. According to Captain Beaumont, the difficulties which might have been expected from windy weather were not considerable, and twenty-five or thirty men sufficed to convey the balloon easily, when inflated, over all obstacles. The transport of the bulk of the rest of the apparatus does not read, on paper, a very serious matter. The two generators required four horses each, and the acid and balloon carts as many more. Arrived on the scene of action, the drill itself was a simple matter. A squad of thirty men under an officer sufficed to get the balloon into position, and to arrange the ballast so that, with all in, there was a lifting power of some thirty pounds. Then, at the word of command, the men together drop the car, and seize the three guy ropes, of which one is made to pass through a snatch block firmly secured. The guy ropes are then payed out according to the directions of the aeronaut, as conveyed through the officer.