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THE POPULAR SCIENCE MONTHLY.

lished in the annals of the New York Academy of Sciences, one hundred and seventy-five plates of the sun, one hundred and seventy-four of the solar spectrum, four hundred and thirty-five of the moon, and six hundred and sixty-four of star clusters. The reduction of the measures of the Pleiades plates, taken with the thirteen-inch instrument and measured with the improved machine, undertaken according to the understanding between Mr. Rutherfurd and the college authorities by Prof. Rees and Mr. Harold Jacoby of the observatory, and completed and published only a few days before Mr. Rutherfurd's death, but too late to be examined by him, seem, says Prof. Rees, to indicate an accuracy of measures comparable with the best recent heliometer work. Yet they were all taken between 1865 and 1874. It is intended to continue the reductions till all the measures made with the improved machine—filling some twenty folio volumes of about two hundred pages each—are finished; then to measure the negatives that remain unmeasured, and proceed to their reduction.

Prof. Gould emphasizes the fact that all these plates were made some years before the discovery of the dry-plate process, by the aid of which celestial photography has made such wonderful progress in recent years; and "we owe to him not merely the first permanent records of the relative positions, at a given moment, of all the celestial objects impressed upon the sensitive plates, but the means and the accomplishment of the actual conversion of these records into actual numerical data."

Mr. Rutherfurd demonstrated, contrary to the prevailing opinion, that the albuminated collodion film could be made stable on glass under all conditions of atmospheric change.

Mr. Rutherfurd was a member of the International Meridian Conference that met in Washington in October, 1885, and took a prominent part in its work, framing and presenting the resolution that embodied the conclusions of the conference. He was invited by the French Academy of Sciences in 1887 to become a member of the International Conference on Astronomical Photography held in Paris in that year, and was given by the President of our National Academy of Sciences the appointment as its representative, but the condition of his health forbade his serving. He was an Associate of the Royal Astronomical Society. He was an original member of the National Academy of Sciences, which was incorporated by act of Congress in 1863. In 1867 he was elected President of the American Photographical Society, in the official board of which he had served for many years as first vice-president. During his administration the society became the Photographical Section of the American Institute. For many years he was not only a trustee of Columbia College, but one of the most active and hard-working members of that body. Mr. Ruth-