re 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.

The balloon accompanied the army's advance where its services could be
turned to the greatest advantage. It was employed in making continual
ascents, and furnishing daily reports to General M'Clellan, and it was
supposed that by constant observation the aeronaut could, at a glance,
assure himself that no change had taken place in the occupation of the
country. Captain Beaumont, speaking, be it remembered, of the military
operations and manoeuvres then in vogue, declared that earthworks could
be seen even at the distance of eight miles, though their character
could not be distinctly stated. Wooded country was unfitted for balloon
reconnaissance, and only in a plain could any considerable body of
troops be made known. Then follows such a description as one would be
expecting to find:--

"During the battle of Hanover Court House, which was the first
engagement of importance before Ric