A careful study of the early history of the Harvard College Observatory has been made by Mr. Daniel W. Baker. Many facts were thus brought to light which had not appeared in print. A series of newspaper articles was accordingly prepared, which were published in the Boston “Evening Traveller” on six successive Saturdays, beginning August 2, 1890. Much of this material appearing to be of sufficient value for preservation in a more permanent form, it has been reprinted in the present pamphlet, with slight alterations, and with the addition of the illustrations given on page 25. The parts numbered IV. and V. originally appeared together as a single article. Reproductions have been made of some of the illustrations. The articles were originally addressed, not to professional astronomers, but to the general public, and are to be regarded as a popular description of the work accomplished at the Harvard College Observatory during the first fifty years of its existence.