Part I of Mr. Ogilvie’s book is entitled, “The Evolution of the Principle” and is intended to serve as an introduction to the subject of internatitonal rights on inland navigable waterways. Systematic treatment of the subject is reserved for a later volume. Assuming that free navigation on inland waterways is the natural sequence of freedom on the seas, the author sketches briefly the growth of maritime enterprise, the early development of maritime law, the history of maritime discovery, and the triumph after long controversy of the freedom of the seas- One short chapter is devoted to freedom of navigation on inland waterways. Notwithstanding its somewhat superficial and fragmentary character, this part of the book will be of interest to those who have no time in which to read the more exhaustive and scholarly works upon which the author mainly relies. Part II is a unique and an invaluable contribution. It is .a reference manual to the treaties, conventions, laws, and other fundamental acts which govern the use of inland waterways. The water highways of the world are grouped according to continents and listed in alphabetical order under each continent. Documents are arranged in alphabetical order under each waterway and the more important documents are accompanied by selected references to secondary sources. The entire manual is covered by an exhaustive index. All who are interested in the subject of treaty rights on inland waterways, whether in connection with practice or with research, will find this reference manual an indispensable guide.