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408 British Association for the Advancement of Science. Through the urgency of Sir David Brewster and others it was set up in the great exhibition of that year in London, where a medal was awarded for it. It was adopted at the Greenwich Observatory soon after, and speedily throughout Europe. The use of the "circuit interrupter" and the "chronograph" together constitute what became known in Europe as "the American method" of recording observations. Through it the errors for which the "personal equation" is a partial remedy are largely eliminated, and a superior definiteness of record is attained.

Soon after the electrical experiments of 1848, the "circuit interrupter" was put to use at Cambridge in transmitting to Boston and other points in New England the true local time. This was the beginning of the Harvard Observatory time-service, which was systematically organized in 1872. This idea was also early adopted at Greenwich.

In 1852 the officers of the Harvard Observatory co-operated with Captain Charles Wilkes in experiments for ascertaining the velocity of the sound from the discharge of cannon under different atmospheric conditions. The object of this investigation was to secure accurate values for some of the data obtained by the exploring expedition, the measurement of distances in some cases having been made by firing cannon.

One of the important events in the latter part of Prof. Bond's directorship of the Observatory was the beginning of the publication of The Annals of Harvard College Observatory. This was made possible by an endowment of ten thousand dollars given in 1855 by Josiah Quincy, ex-president of the college. The first of these noble quarto volumes was issued in the following year, and embodied a review of the work of the preceding years, so that the whole series makes a continuous record from the establishment of the observatory.

Prof. Bond died January 29, 1859, and was succeeded in the management of the Observatory by his son, George Phillips Bond, who had been one of his assistants for many years. The elder Bond had entered vigorously into the scientific life of his time, and his labors were duly appreciated by his associates and contemporaries. He was a member of the American Academy of Arts and Sciences, the American Philosophical Society, and the Royal Astronomical Society of England. From Harvard College he received the honorary degree of A. M. in 1842.