"In 1860, shortly after the death of his wife and newborn son, Brewer was invited by Josiah D. Whitney to become the chief botanist of the California Division of Mines and Geology (predecessor of today's California Geological Survey). Brewer led field parties in the extensive survey of the geology of California until 1864, when he became the Chair of Agriculture at Sheffield Scientific School. Brewer wrote extensively during the survey including many letters to family and friends, a compendium of which was eventually published by the Yale University Press in 1930 as Up and Down California in 1860-1864. " (from Wikipedia) .