Significados de free balloons en inglés

Some, at least, of the methods formerly recommended for the management of free balloons must in these days be modified.

The Siege of Paris showed the utility of free balloons, and occasions arise when their use might be still further extended.

Since planes could not report the progress of the snowshoers over the grass, dirigibles and free balloons drifting with the wind gave minutetominute reports.

Distinct from, and supplementing, the records obtained by free balloons, manned or unmanned, are those to be gathered from an aerostat moored to earth.