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     Technical and scientific men, such as are assembled to celebrate the dedication of the magnificent new buildings of the Massachusetts Institute of Technology, may be interested to know of the technical work that led to the building of this first successful flying machine. The mind of man had been occupied with the problem of flight for many centuries, but the greater part of the work done was not of a scientific character. When the Wrights took up the subject in 1896, only a few aerodynamical works of scientific interest were in existence. Engineers at that time in calculating air pressures used the tables of Lilienthal and Duchemin. The work of lyingly seems to verify the Duchemin formula. But after two years of experiment with machines based upon the tables of Lilienthal and Duchemin, the Wrights became convinced that these tables were so far in error as to be of no value in the designing of an aeroplane. They therefore in 1901 constructed a small wind-tunnel in which to make measurements of the pressures produced by various shaped surfaces when exposed to the air at different angles. For making the measurements they use the type of instrument which they thought would almost entirely eliminate the factors which had spoiled the measurements of their predecessors. During the winter of 1901-1902 they tested altogether more than one hundred different surfaces in this tunnel, and tabulated the results of the measurements of about fifty of them. They made measurements of square and rectangular surfaces in order to determine the effect of varying the ratio of the length and breadth of the surfaces. They also made measurements to ascertain the effects of, and possible advantages in using, curved instead of plane surfaces, and the effects of varying the depth of curvature as well as the location on the maximum depth of curvature. They measured thick and thin surfaces to determine the effects of thickness, and also surfaces with maximum thickness at different points. They determined the effects on surfaces when superposed and when one followed the other. They measured the travel of the center of pressure on curved surfaces when exposed to the air at different angles. No tables of the travel on curved surfaces were in existence at that time.
     With the results of these laboratory experiments at hand, and with a system of control already developed by themselves in their gliding experiments of 1900 to 1902, the Wrights were in a position to design and build a power-driven aeroplane, with hope of success. This first machine of 1903 was designed entirely from the tables of air pressures worked out in the laboratory. At that time there was no published data on air propellers. The Wrights designed these first propellers on a theory of screw propulsion worked out by themselves. The result was the development of over sixty-six per cent. efficiency, and efficiency which has been rarely exceeded either in marine or air propellers to-day.