Man’s conquest of the air has accelerated so rapidly in recent years that even a professional observer must look sharp to remain current. The Wright Brothers first flew in 1903. Last year, more than thirteen million passengers flew on scheduled American airlines. Lindbergh’s Spirit of St. Louis was the first airplane to cross the Atlantic non-stop from America to the European mainland in 1927. Today forty commercial planes span the same ocean every twenty-four hours. An airplane first flew faster than 400 miles per hour in 1934. Today “supersonic” speeds are commonplace, and a new word, “hypersonic”—for speeds far, far beyond the sonic range—is now in use.