In 1877, in co-operation with Miss Mitchell of Vassar College Observatory and her assistants, observations were made at Cambridge for determining the longitude of the Vassar Observatory. Between Feb. 15, 1879, and Jan. 3, 1880, like observations were made in co-operation with officers of the Winchester Observatory of Yale College to ascertain the longitude of that institution. Between June 2 and June 23, 1883, similar work was done to fix the longitude of McGill Observatory in Montreal. In the summer of 1888 ten evenings were given for observations for the longitude of Smith College in Northampton. The observers were Miss Byrd, teacher of astronomy at that college, and Miss Whitney, professor of astronomy at Vassar College. Harvard’s contribution in the affair consisted in providing facilities on the spot, including the use of a transit instrument. These are instances, which among others go to show that because of infinite painstaking at Harvard in the earlier years it has become the Mecca to which all on this continent who wish to be perfectly assured in the matter of longitude may prudently make a pilgrimage. In 1881 an arrangement was entered into for prompt communication as to unusual celestial phenomena, discoveries, etc., among astronomers in this country and in Europe. A cipher code, the invention of Messrs. S. C. Chandler and John Ritchie, Jr., of the observatory staff, was put into use. It is known as the “Science Observer Code,” and as it is superior in accuracy to former codes has been widely recognized. In 1883 Harvard observatory was made the official distributing centre for this class of news, by consent of the Smithsonian Institute, which had previously performed the service. Upon the occasion of the transit of Mercury across the sun’s disk in May, 1878, all the available telescopes of the observatory were put to use. The results, which included many photographs, were satisfactory, considering the unfavorable weather. During the like transit of Venus, on Dec. 6, 1882, six telescopes being in use, large additions were made to the important data which planetary events of this kind may supply. In August, 1886, a small party provided with instruments belonging to the observatory made an expedition to Grenada, near the northern coast of South America, for observation of the total solar eclipse of that year. The expedition was in charge of Mr. W. H. Pickering, who afterwards became a member of the observatory corps. On Jan. 1, 1889, a large party, under the same direction, observed a recurrence of the event in California. The observations were mainly photographical. Excellent results were obtained in both cases, though less in amount in the former, because of unfavorable weather.