Much of the work done at the Harvard Observatory is in cooperation with other observatories and meteorological stations. In cooperation with the Blue Hill Meteorological Observatory, under the direction of Mr. A. L. Rotch, Assistant in Meteorology. Meteorological observations are maintained and the results published in the Annals of the Observatory.

In cooperation with the New England Weather Service, observations are made at nearly two hundred stations distributed over New England, and the results are published in the Annals, which also contain the results of investigations by members of the New England Meteorological Society.

By the mutual consent of astronomers, the Kiel and Harvard Observatories have been selected as the centres for the prompt announcement of astronomical discoveries. For example, when a comet is discovered in America its position is telegraphed to this observatory, from here to Kiel, and thence to all the principal observatories of Europe.

Forty assistants take part in the work of the observatory. The results obtained are published in a series of Annals, and now fill thirty quarto volumes. The preparation of these volumes occupies a large part of the force at the observatory in Cambridge. Besides this labor, a large amount of observation is done there, several instruments being kept in constant use. The largest of these are the fifteen-inch and six-inch equatorial telescopes, the eight-inch transit circle, the eleven-inch Draper photographic telescope, the eight-inch photographic telescope, and the meridian photometer.

Instruction in astronomy is not given at the observatory, either by lectures or recitations. Facilities are freely offered to astronomers for making use of the library, buildings, grounds, and instruments of the observatory, so far as this can be done without interfering with regular work. Similar opportunities are sometimes offered to special students in astronomy, but the constant employment of the principal instruments greatly limits the use that can be made of them for this purpose.