Aeronautics. Our ordinary dull and commonplace method of locomotion upon the surface of the earth has for many ages incited men of an enterprising turn of mind to give their attention to rising in the air, and attempting to soar aloft through the upper regions. The engineer and the student of mechanical science know that there is nothing unreasonable or inconsistent in the possibility of commanding locomotion through the air over the land and the water. The problem of producing motion in a given direction through the air is somewhat analogous with that of producing motion in a given direction through the water. The complete form of the problem of aerial navigation is, of course, that of flying; and the study of the mechanical condition of that wonderful process is one of the most interesting offered by Nature.
In 1670 an Italian Jesuit of the name of Francis Lana first published a project, in which he proposed to rise in the air by the aid of four copper balls from which the air had been exhausted to form a vacuum. In 1766 a Doctor Black, and in 1782 an Italian named Cavallo, were also actively at work in trying to solve aerial navigation. About the year 1782 a new departure took place, when the Brothers Montgolfier introduced the balloon, and thus overcame the great obstacle to aerial navigation caused by the action of gravity, and so simplified the conditions as to bring the problem much more within the reach of practical skill. After a number of experiments, Stephen and Joseph Montgolfier were convinced that a certain degree of heat would considerably diminish the weight of air.
They then experimented with balloons made of silk and linen, filled with hot air and smoke made by burning chopped straw and wood. These experiments proving successful, they next sent up a linen balloon, 30 feet in diameter, which had nothing to lift except its own weight. It therefore rose to a great height, and descended in a field a mile and a half away. The next experimental balloon carried a car, in which were a sheep, a cock, and a duck, which proving successful, induced M. Pilatre de Rozier and the Marquis d'Arlandes to ascend in a balloon 45 feet in diameter and 75 feet high. They started about two o'clock in the day, and passed over Paris, much to the astonishment of the people. The balloon attained an altitude of over half a mile, and was inflated with hot air. Ballast was for the first time employed for regulating the ascending power of the balloon.
The first gas-inflated balloon was invented by Professor Charles, which ascended in December, 1783, from the Tuileries.
M. Henri Giffard, the inventor of the ' Injector,' in 1852, made the first attempt to utilise the screw for balloons. As a power to work his screw he used a steam engine. M. Depuy de Lome in 1872 made a successful ascent in an elongated shape balloon; the car carried a screw propeller of two sails with a view of giving a velocity to the balloon independent of the wind.
While France can claim the initiators of the science of Aeronautics, England has furnished the most successful operators, for Messrs. Glaisher and Coxwell in 1862 accomplished the highest ascent which has yet been made, rising to the enormous height of 7 miles.
The aerostat is in appearance the shape of a large fish. A car is underneath; and at one end of the inflated spheroid is a projecting wing-like object, used as a rudder.
The rudder consists of a sail, 39 feet square, which projects outside the car like that of a boat.
The screw propeller, or aerial screw, is at the front end of the balloon, and is rotated at a swift rate by the "Gramme" machine, which is itself worked by the current from a battery of accumulators or voltaic cells. The gas envelope is made of light, strong silk, covered with a netting, from which the platform or car is hung.
The error into which most persons have fallen in attempting aerial locomotion is the futile endeavour to fly, after the manner of those creatures which are specially adapted by Nature for that purpose.
In these days of scientific discoveries it cannot be said that flying by mechanical means will never be accomplished, but it is doubtful whether it would be of practical use in all states of the atmosphere.
Now, to accomplish aerial locomotion it is necessary to give almost as much buoyancy to the body of a man as would enable it to remain suspended in mid-air. To do tnis it requires a lifting power lighter than the atmosphere. The practical utility of aerial locomotion must always be considerably restricted by the effect of the wind, rain, hail, and snow, which it is impossible for any flying body to evade; and, on the whole, balloons which can be so constructed as to dispense with ballast, and rise and fall at the will of the aeronaut, and thus utilise the currents going at different altitudes in different directions, will at some future date form a feasible and useful addition to the present means of transport by sea and land.
The introduction of petroleum, at a moderate cost, for locomotive purposes is already in use; and mineral oils have many advantages over coal and electricity as a motive power. Coal is too heavy for aerial purposes, and electricity has very little effective power. Until some satisfactory method can be discovered for sufficiently controlling balloons, they can never be of very great practical value. They have, however, been used with some success in military operations, notably during the siege of Paris 1870-71; and in 1886 M. L'Hoste and M. Mangot, French aeronauts, successfully steered a balloon, by the aid of a sail, ropes, and floating anchor, from Cherbourg to the Isle of Wight. By the aid of the screw they were enabled to bring the balloon to within a few yards of the water, drop the floating anchor, and hoist the sail, and thus guide the balloon in the desired direction. They were thus enabled to maintain a low altitude, and counteract the heat from the sun's rays, which tends to raise the balloon to higher currents, by letting down a can in the water, which was filled, raised, and emptied in a reservoir fixed below. They thus proved for the first time the power and direct control of balloons travelling over the sea.