In the years between 1900 and 1931 astronomers witnessed three startling changes in their view of the Universe. First, the accepted value of the size of the star system, which increased by a factor of ten; secondly, evidence forced the acceptance of the fact that there are other star systems beyond our own Galaxy; and lastly, that observation of these external galaxies disclosed the expansion of the Universe. This book, originally published in 1982, describes and explains in detail these shifts in opinion, considering them in the light of theories and ideas on the nature of the Universe, were...

The period between 1775 and 1815 could be called the -critical period- of American foreign relations. At no time in American history was the existence of the republic in greater physical peril. Questions of foreign policy dominated American public life in a way unequalled until World War II. From the American Revolution through the War of 1812, the United States was a small power confronted by great powers hostile to each other and to the United States. Furthermore, the era was dominated by two great revolutions that reshaped the Atlantic world. The problem for American diplomats and foreign...