Nicollet was born at Cluses, in Savoy, in 1786. First a cowherd, he did not learn to read until he was twelve. Once at school his progress was rapid, and at nineteen he become preceptor of mathematics at Chambry. He went to Paris, where in 1817 he was appointed secretary-librarian of the Observatory, and he studied astronomy with Laplace, who refers to Nicollet’s assistance in his works. In 1823 he was appointed to the government bureau of longitudes, and at the same time was professor of mathematics in the College of Louis le Grand. He became a master of English, and through this knowledge and his own mathematical genius he was able to assemble, for the use of the French life-insurance companies, all that was known, and much that he himself discovered, of actuarial methods; this being incorporated in his letter to M. Outrequin on “Assurances Having for Their Basis the Probable Duration of Human Life.” He also wrote “Memoirs upon the Measure of an Arc of Parallel Midway Between the Pole and the Equator” (1826), and “Course of Mathematics for the Use of Mariners” (1830). In 1831 Nicollet failed in speculation, losing not only his own fortune but that of others. He came to the United States, arriving early in 1832, the very year that Locke came to America. It is probable that he was in New York, but there is no evidence as to the length of his stay. It is known, however, that he was impoverished, and that he was assisted by Bishop Chanche, of Natchez, to go on with his chosen work--an exploration of the Mississippi and its tributaries. He made astronomical and barometrical observations, determined the geographical position and elevation of many important points, and studied Indian lore. The United States government was so well pleased with Nicollet’s work that it sent him to the Far West for further investigations, with Lieutenant John C. Frémont as assistant. His “Geology of the Upper Mississippi Region and of the Cretaceous Formation of the Upper Missouri” was one of the results of his journeys. After this he tried, through letters, to regain his lost standing in France by seeking election to the Paris Academy of Sciences, but he was black-balled, and, broken-hearted, he died in Washington in 1843. The Englishman who believed that Nicollet was the author of the moon hoax was Augustus De Morgan, father of the late William De Morgan, the novelist, and himself a distinguished mathematician and litterateur. He was professor of mathematics at University College, London, at the time when the moon pamphlet first appeared in England. His “Budget of Paradoxes,” an interesting collection of literary curiosities and puzzles, which he had written, but not carefully assembled, was published in 1872, the year after his death. [Illustration: THE FIRST INSTALLMENT OF THE MOON HOAX ] [Illustration: A MOON SCENE, FROM LOCKE’S GREAT DECEPTION ] Two fragments, printed separately in this volume, refer to the moon hoax. The first is this: