COOLIDGE, Sidney, scientist, born in Boston, Massachusetts, in 1830; died near Chickamauga, Georgia, 19 September, 1863. He studied abroad from 1839 till 1850, first in Geneva and Vevay, and afterward in the Royal military College in Dresden. After his return to this country he assisted in the construction of the Richmond and Danville railroad, and in running the boundary-line of Minnesota. After working in the nautical-almanac office and in the Cambridge observatory, he was appointed in 1853 assistant astronomer to Com. Perry's Japan exploring expedition. In 1854 he assisted Prof. George P. Bond in his observations of the planet Saturn, and contributed drawings and notes to the published annals of the observatory. He took charge in 1855 of the chronometric expedition for determining the difference of longitude between Cambridge and Greenwich, and in 1856-'7 studied the dialects and astronomical superstitions of the Indians near Saguenay River and Lake Mistassinnie. Being in Mexico in 1858, he took part in the civil war of that year, was taken prisoner and sentenced to be shot, but was finally released and sent to the City of Mexico on parole. He took part in an Arizona land-survey in 1860, and in May, 1861, became major in the 16th United States infantry. He was superintendent of the regimental recruiting service in 1862, commanded regiments at different posts and camps, and was engaged at the battles of Hoover's Gap and Chickamauga, where he was killed. For his services in the latter fight he received the brevet of lieutenant colonel.