I should like to thank those who helped me with this book, most particularly two former members of China's Customs Service. G. R. G. Worcester lent me books and suggested many sources. Rolla Rouse, who was a Commissioner of Customs from 1923 to 1950, not only gave me the run of his valuable collection of material dealing with Customs affairs, but read the manuscript carefully, pointing out errors and referring me to the proper authorities with which to check the facts. It was a time-consuming task, and I am very grateful to Mr. Rouse.