[Illustration: One of Dr. Langley’s first models; a biplane with flexible wing-tips and twin propellers. 1889.] ~EARLY TYPES OF FLYING MACHINES~ M. A. Penaud, a Frenchman, in experimenting with models, seems to have been the first to discover the necessity of vertical and horizontal rudders in maintaining balance. Mr. Horatio Phillips, an Englishman, discovered, and patented, the use of curved instead of flat surfaces for the planes. Otto and Gustav Lilienthal are said to have been the first to attempt to balance aeroplanes by flexing or bending the wings. Various others, including Messrs. Richard Harte, Boulton, Mouillard, worked out ideas for balancing machines by the use of auxiliary planes which could be set at different angles with regard to the line of flight, thus forcing the machines to different positions by the force of the air rushing against them. Dr. Langley, trained in scientific investigation, conducted an elaborate series of experiments covering many years and costing thousands of dollars to test and prove the value of the claims of the earlier investigators. Some things which he thought he was the first to discover,--such as the effect of the vertical and horizontal rudders,--he later found had already been proven by others. Independently he covered the entire field of experiment and after building hundreds of small models he succeeded, in 1896, in making a machine weighing several pounds equipped with a very light steam engine which flew safely as long as the fuel lasted. For his early experiments Dr. Langley was afforded financial assistance by Mr. William Thaw of Pittsburg. After the success of his small machines Dr. Langley was asked to undertake the construction of a large, man-carrying machine, and Congress voted him $50,000 to carry on the work. A large share of this was spent on the development of a very light gasoline engine. The machine finally was completed, but was twice broken through defective launching apparatus. Congress and Dr. Langley were so ridiculed by the public press that the machine was temporarily abandoned. Not, however, until after Dr. Langley had successfully flown a steam driven machine much larger than many of the racing aeroplanes of today. But eight years after Dr. Langley’s death, which is said to have been due to the heart-breaking disappointment he suffered in trying to demonstrate the large machine, Glenn H. Curtiss, at the request of the Smithsonian Institution, rebuilt the old Langley machine and succeeded in making a flight with it at Hammondsport, N. Y., on May 28, 1914. [Illustration: THE FIRST MAN-CARRYING AEROPLANE First successful man-carrying aeroplane. Designed by Dr. Langley in 1898; flown by Glenn H. Curtiss at Hammondsport, N. Y., 1914.] [Illustration: Front view of big Langley machine in 1914.]