The grateful acknowledgments of the author are due to Mr. William Joseph Showalter for his valuable aid in gathering and preparing the material for this book. Acknowledgments are also due to Colonel George W. Goethals, chairman and chief engineer of the Isthmian Canal Commission, for reading and correcting those chapters in the book pertaining to the engineering phases of the work; to Mr. Ernest Hallen, the official photographer of the Commission, for the photographs with which the book is illustrated; to Mr. Gilbert H. Grosvenor, editor of the National Geographic Magazine, for permission to use the bird's-eye view map of the canal; to Mr. G. Thomas Ritchie, of the Library of Congress, for assistance in preparing the index; and to Mr. Howard E. Sherman, of the Government Printing Office, for revising the proofs to conform with the typographical style of the United States Government.