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 576 FAMOUS LIVING AMEEICANS of gliding, as they had hoped, they had only two minutes of actual sailing that year. Nevertheless they came to some very satisfactory conclusions. The new method of steering and balancing by shifting surfaces instead of weights worked well and promised to work as well in larger machines. In 1901 they were again at Kitty Hawk with a machine, this time nearly twice as large as had been counted safe before. It had a surface of 308 square feet, measured twenty-two feet from tip to tip, and weighed with the operator about 250 pounds. Its trial flights were so successful that in 1902 they construct- ed another glider on advanced lines. Some seven hundred to a thousand glides were made that year, the longest of which was 622 feet. In addition, they established definitely many corrections in the tables of calculations for aerial flight. These experiments were not mere slides down an inclined plane in the air, for often the machine would be lifted above the point of starting and held soaring in one place for as long as half a minute. Thus far they had been experimenting purely for sport, but one day an eminent engineer and authority in flying, Dr. Oc- tave Chanute of Chicago, appeared on the ground, carefully observed their flights, and studied their calculations. He startled them into seriousness by saying that they had gone ahead of all others in the conquest of the air. With a dawn- ing and overwhelming appreciation of the value of these en- couraging words, they began to give more thought to the sub- ject and to spend more time away from their Dayton bicycle shop. Having now accurate data for making calculations and a system of balance eflFective for winds as well as calm, they built their first power machine. The first designs provided for a total weight of 750 pounds. The screw-propellers which they intended to use were not easily designed although they were simply wings traveling in a spiral course. They found that the theories of the marine engineers were unreliable and once more the Wrights wrestled with an unsolved problenu When at last they arrived at a clear understanding of the diffi-