factories. At the Northern station plain white calico was used, sewn
with a sewing machine, whereas at the Orleans station the material was
coloured and entrusted only to hand stitching. The allimportant detail
of varnish was supplied by a mixture of linseed oil and the active
principle of ordinary driers, and this, laid on with a rubber, rendered
the material gas-tight and quickly dry enough for use. Hundreds of
hands, men and women, were employed at the two factories, at which some
sixty balloons were produced before the end of the siege. Much of
the more important work was entrusted to sailors, who showed special
aptness, not only in fitting out and rigging the balloons, but also in
their management when entrusted to the winds.

It must have been an impressive sight for friend or foe to witness the
departure of each aerial vessel on its venturesome mission. The bold
plunge into space above the roofs of the imprisoned city; the rapid
climb into the sky and, later, the pearl drop high in air floating
away to its uncertain and hazardous haven, running the gauntlet of
the enemy's fire by day or braving what at first appeared to be equal
danger, attending the darkness of night. It will be seen, however, that,
of the two evils, that of the darkness was considered the less, even
though, with strange and unreasonable excess of caution, the aeronauts
would not suffer the use of the perfectly safe and almost indispensable
Davy lamp.

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 ballas