AcknowledgmentsIn exploring a subject as big as the sky I have come upon somuch stimulating material that I have been able to use only asmall part of it in this book. And yet for even that portion I amindebted to the generosity and diligence of scores of persons duringthe ten years it has taken me to get it down to earth and ink.Most difficult to put into words is my wife Kathe7s share — shewho labored long to remove distractions and who understood thata man may be working even when gazing dreamily at the sky.Next I must express my profound debt to Wolfgang Langewiesche,and particularly for his published work which has beenso close in subject to my own and of such excellence that it hastaken much restraint for me to quote him as few as half a dozentimes herein. But far beyond the quotations Mr. Langewieschehas generously allowed me to take from his book, A Flieis World,I owe much to him in inspiration and factual information on thesubjects of air masses, aerodynamics, the engineering problems oflong-range flight, and the mysteries of the sonic barrier.
