Owing to the increasing rarity of the atmosphere as we ascend from the earth’s surface, balloon cases are made very much larger than is required to contain the necessary quantity of gas, to allow for its expansion as it rises into a rarer medium. A cubical foot of gas measured at the level of the sea occupies a space of two feet at an elevation of 31⁄2 miles.
The following Table will prove useful to the amateur aëronaut or balloonist:—
Table showing the relations between the diameters, surfaces, and capacities of spheres.
| Diameters. | Surfaces. | Cubical contents. |
| 1 | 3·141 | ·523 |
| 2 | 12·567 | 4·188 |
| 3 | 28·274 | 14·137 |
| 4 | 50·265 | 33·51 |
| 5 | 78·54 | 65·45 |
| 10 | 314·159 | 523·6 |
| 15 | 706·9 | 1767·1 |
| 20 | 1256·6 | 4189· |
| 25 | 1963·5 | 8181· |
| 30 | 2827· | 14137· |
| 40 | 5026· | 33510· |
See Atmosphere, Gas, Hydrogen, Parachute, Varnish, &c.
BALLOON′ING‡. Syn. Balloon′ry†*. The act, art, or practice of ascending or travelling in balloons; aërostation. A BALLOON′IST‡ is an aëronaut (particularly an amateur or enthusiastic one).
BALLS. The application of this term in commerce, perfumery, veterinary medicine, &c., has been already noticed. (See Ball.) The following may be inserted here:—
Balls, Al′mond (ah′-mŭnd). Syn. Boules d’amande, Fr. Prep. 1. Spermaceti, 4 oz.; white wax (pure) 8 oz.; oil of almonds, 1 pint; melt them together in a glazed earthenware-vessel, by the heat of a water bath, and when the mixture has cooled a little, add essential oil of almonds, and expressed oil of mace, of each 2 dr.; stir assiduously until it begins to cool, and then pour it into the moulds, which may be ounce-gallipots with smooth bottoms (very slightly warmed), when it will form beautiful hemispherical cakes. Very fine.
2. Hard clarified suet, 11⁄4 lb.; white wax, 1⁄4 lb.; ess. oil of almonds, 11⁄2 dr.; oil of cloves (or of pimento), 1⁄2 dr.; as before.
Uses, &c. To soften the skin, and in winter to prevent chaps and chilblains. Sometimes these balls are coloured, which is done whilst the mixture is in the liquid state. A rich pink or red may be given by a little alkanet-root or dragon’s blood; a yellow, by palm oil or annotta; a blue, by a little finely powdered indigo; and a green, with spinage (steeped in the oil before use), or a few grains of verdigris. The most appropriate tint for them is a pale yellow or amber.