The idea of constructing a machine which should enable us to rise into and sail through the air, seems often to have occupied the attention of mankind, even from remote times, but it was never realised until within the last sixty or seventy years. The first public ascent of a fire-balloon in France, in 1783, led to an experiment on the part of Joseph Mongolfier. He constructed a balloon of linen, lined with paper, which, when inflated by means of burning chopped straw and coal, was found to be capable of raising 500 pounds weight. It was inflated in front of the Palace at Versailles, in the presence of the Royal family, and a basket, containing a sheep, a duck, and a cock, was attached to it. It was then liberated, and ascended to the height of 1500 feet. It fell about two miles from Versailles; the animals were uninjured, and the sheep was found quietly feeding near the place of its descent. Monsieur Mongolfier then constructed one of superior strength, and a M. de Rozier ventured to take his seat in the car and ascend three hundred feet, the height allowed by the ropes, which were not cut. This same person afterwards undertook an aerial voyage, descending in safety about five miles from Paris, where the balloon ascended. But this enterprising voyager in the air afterwards attempted to travel in a balloon with sails. This was formed by a singular combination of balloons--one inflated with hydrogen gas, and the other a fire-balloon. The latter, however, catching fire, the whole apparatus fell from the height of about three-quarters of a mile, with the mangled bodies of the voyagers attached to the complicated machinery. [Illustration: GREEN'S BALLOON, ASCENDING FROM VAUXHALL GARDENS.] A Frenchman named Tester, in 1786, also made an excursion in a balloon with sails; these sails or wings aided in carrying his balloon so high, that when he had reached an elevation of 3000 feet, fearing his balloon might burst, he descended into a corn-field in the plain of Montmorency. An immense crowd ran eagerly to the spot; and the owner of the field, angry at the injury his crop had sustained, demanded instant indemnification. Tester offered no resistance, but persuaded the peasants that, having lost his wings, he could not possibly escape. The ropes were seized by a number of persons, who attempted to drag the balloon towards the village; but as, during the procession, it had acquired considerable buoyancy, Tester suddenly cut the cords, and, rising in the air, left the disappointed peasants overwhelmed in astonishment. After being out in a terrible thunder-storm, he descended uninjured, about twelve hours from the time of his first ascent. * * * * * SIR THOMAS GRESHAM. [Illustration: Letter A.]