Mr. Parsons' book is a grindingly thorough account of the first joint Anglo-American surveying expedition (1872-76) along the 49th parallel which permanently fixed the boundaries separating the United States and Canada. The book explains why ""today only one boundary monument in a thousand stand precisely at 49 degrees north latitude"". The story is told from diaries and letters and from both the U.S. and British viewpoints. For the most part, the surveyors and their troops pressed through uncharted territory. The author itemizes provisions, lists miles of ground covered, reports on winter activities, Indian customs, villages encountered, animosities between the U.S. and British expeditionaries. His anecdotes are scant and short. There are thumbnail portraits of several leaders who are not particularly memorable. There is one fascinating passage, in the appendix: a voyage down the Missouri in 1874 by one Lt. Francis Greene, which is a long letter and printed verbatim. Otherwise, this must rest as dutiful official history.