The first very light engine to be available was the _Antoinette_, built by Leon Levavasseur in France. It enabled Santos-Dumont to make his first public successful flights. Nearly all aeroplanes follow the same general principles of construction. Of course a good deal depends upon the form of aeroplane--whether a monoplane or a biplane. As these two forms are the chief ones, as yet, of heavier than-air machines, it would be well to understand them. The monoplane has single large surfaces like the wings of a bird, the biplane has two large surfaces braced together one over the other. At the present writing a triplane has been introduced into the domain of American aviation by an English aeronaut. Doubtless as the science progresses many other variations will appear in the field. Most machines, though fashioned on similar lines, possess universal features. For instance, the Wright biplane is characterized by warping wing tips and seams of heavy construction, while the surfaces of the Herring-Curtiss machine, are slight and it looks very light and buoyant as if well suited to its element. The Voisin biplane is fashioned after the manner of a box kite and therefore presents vertical surfaces to the air. Farman's machine has no vertical surfaces, but there are hinged wing tips to the outer rear-edges of its surfaces, for use in turning and balancing. He also has a combination of wheels and skids or runners for starting and landing. The position to be occupied by the operator also influences the construction. Some sit on top of the machine, others underneath. In the _Antoinette_, Latham sits up in a sort of cockpit on the top. Bleriot sits far beneath his machine. In the latest construction of Santos-Dumont, the _Demoiselle_, the aviator sits on the top. Aeroplanes have been constructed for the most part in Europe, especially in France. There may be said to be only one factory in America, that of Herring-Curtiss, at Hammondsport, N.Y., as the Wright place at Dayton is very small and only turns out motors and experimenting machines, and cannot be called a regular factory. The Wright machines are now manufactured by a French syndicate. It is said that the Wrights will have an American factory at work in a short time. The French-made aeroplanes have given good satisfaction. These machines cost from $4,000 to $5,000, and generally have three cylinder motors developing from 25 to 35 horse power. The latest model of Bleriot known as No. 12 has beaten the time record of Glenn Curtiss' biplane with its 60 horse power motor. The Farman machine or the model in which he made the world's duration record in his three hour and sixteen minutes flight at Rheims, is one of the best as well as the cheapest of the French makes. Without the motor it cost but $1,200. It has a surface twenty-five meters square, is eight meters long and seven-and-a-half meters wide, weighs 140 kilos, and has a motor which develops from 25 to 50 horse power.