running animals: their gases are probably several degrees lighter.

"Azote or hydrogen, or whatever the gas held in the gaseous structures may be, it is proportionately warmer, and therefore proportionately lighter than air."

1874.

1878. This year Professor Ritchell exhibited at Hartford, Connecticut, a flying machine, the result of many years' study.

The lifting power was obtained from a horizontal cylinder of gossamer cloth coated with india-rubber 25 ft. long by 13 ft. in diameter and weighing 66 lbs. A net-work of worsted bands enclosed the cylinder, which was connected to a strong brass tube 1 ins. in diameter and 23 ft. long, to which the flying machine proper was attached. This consisted of an arrangement of hollow brass rods, very light and strong, which carried the gearing and a four-bladed fan or screw propeller, which could be rotated at the rate of 2,000 revolutions per minute; this propeller was 24 ins. in diameter and was worked by treadles from a small seat, and attached to this gearing was a vertical fan 22 ins. in diameter; the cylinder was filled with hydrogen gas, which made the machine floatable.

The Professor rose with this to a height of 250 feet, sailed over the Connecticut River, and worked his way back by means of the propeller.

Having exhausted the subject of flying machines, the next chapters are on Balloons, and the first persons who tested their theories by actual demonstration, and showed by the best of all proofs the possibility of men rising into the air, were the Messieurs Montgolfiers.

CHAPTER I.

1782 to 1784.

"There's something in a flying horse,
There's something in a huge balloon."

(Translation.)

Wordsworth.

AËROSTATIC MACHINES.

A SHORT EXTRACT from the Appendix to the 69th Volume of The Monthly Review by M. Fanjas de St. Fond.

THE preface to the above volume contains a short survey of what projects have formerly been suggested for the purpose of floating heavy bodies in the atmosphere; the principal which are those of Lana, a Jesuit of Brescia; and of Galieen, a Dominican of Avignon; both of which, however, were, upon well-established principles, found by theory to be impossible in the execution.

Due honour is paid to Mr. Cavallo, of London, who in 1782, seemingly with a view to this discovery, tried to fill bags of paper and

bladders with inflammable air: but failed in his attempts by the unexpected permeability of paper to inflammable air, and the too great proportional weight of the common sized bladders.

The honour of the discovery is certainly due to the brothers Stephen and Joseph Montgolfier, proprietors of a considerable paper manufactory at Annonay, a town about 36 miles south of Lyons, and their invention is the more to be admired, as it is not the effect of the discovery of a permanent elastic fluid lighter than the common air, but of properties of matter long known, and in the hands of many acute philosophers of this and of the last century.

They conceived that the effect they looked for might be obtained by confining vapours lighter than common air in an inverted bag, sufficiently compact to prevent their evaporation, and so light that when inflated its own weight, added to that of the enclosed vapour, might fall somewhat short of the weight of the air which its bulk displaces.

On these principles they prepared matters for an experiment: they formed a bag, or balloon, of linen cloth lined with paper, nearly spherical, about 35 ft. in diameter; its solid contents were about 22,000 cubic feet, a

space nearly equal to that occupied by 1,980 lbs. of common air; of a mean temperature, on the level of the sea, the vapour was about half as light as common air, weighing 990 lbs. The balloon, together with a wooden frame suspended to the bottom which was to serve as ballast, weighed