The main purpose of this research was to determine the transparency of water vapor, under atmospheric conditions, to radiation such as the warm earth sends toward space. Upon the absorptive property of water vapor rests in part the virtue of the atmosphere as a conservator of the heat which the earth receives from the sun. Radiation from the sun reaches the earth's surface diminished by a certain portion scattered toward space and certain other portions absorbed in the gases and vapors of the atmosphere. The return of the energy of this radiation back to space is an indirect process. The warmed earth is cooled partly by convection currents playing over its surface and partly by direct and indirect radiation through the constituents of its atmosphere. Of these the principal hindrances to free radiation are aqueous vapor and carbonic acid gas.

Mr. Fowle's investigations have fixed the dependence of the transmission of the atmosphere on humidity for all wave lengths up to 17 microns. This covers a region of spectrum about fifty times as long as that which is visible to the eye. At about 17 microns rock salt, which is used in preference to glass for optical work on long-wave rays because glass is opaque, itself becomes opaque. Further progress in the important region between 17 and 50 microns depends on finding a new transparent medium. Experiments by Mr. Aldrich have shown that potassium iodide is suitable. But hitherto this substance has yielded no crystals bigger than buckshot. Fortunately, new methods devised for war purposes seem likely to furnish large crystals of this substance and there is great hope that the investigation of atmospheric transparency may soon be carried further.

The total solar eclipse of June 8, 1918, was observed at Lakin, Kans., by Mr. Aldrich, of the Observatory, with two assistants. Some good photographs of the solar corona and other phenomena were secured. Throughout the afternoon and early night hours of June 8 and 9 observations were made with the pyranometer. The results "measure the gradual dimunition of the radiation of the sun and of the brightness of the sky as the eclipse progressed, the outgoing radiation of the earth's surface during totality, the gradual increase of sun and sky radiation afterwards, their decline toward sunset, and the outgoing radiation from the earth's surface after nightfall." Investigations at Mount Wilson of the variability of the sun have been continued and improved. Observations were also made at. Hump Mountain, N. C., but that station was abandoned as too cloudy, and in June, 1918, a station believed to be exceptionally well located was established near Calama in Chile at an altitude of 2,250 meters where meteorological records indicate 300 days per year favorable for solar constant work. This station is supported by a grant from the Hodgkins fund. It is in charge of Mr. A. F. Moore and is exceptionally well equipped.

INTERNATIONAL EXCHANGES.

The total number of packages handled by the International Exchange Service during the year was 266,946, weighing 182,825 pounds, as compared with 399,695 pounds in 1917, the decrease being due almost entirely to war conditions.

The operations of the exchange service have been somewhat curtailed during the past year by the impossibility at times of obtaining cargo space. This condition and the excessively high freight rates necessitated shipments by mail where this could be done advantageously. Notwithstanding the scarcity of shipping, it is significant that governmental licensing boards for imports and exports, both of this country and of Great Britain, have recognized the importance of keeping open the interchange of scientific information by granting licenses to the Institution and its agents for the transmission of this material. Only three consignments of exchanges have been lost through hostile action since the beginning of the war.

In the interchange of Government publications 91 sets of United States governmental documents were received for distribution to designated depositories in foreign countries.

INTERNATIONAL CATALOGUE OF SCIENTIFIC
LITERATURE.

The United States Bureau of the International Catalogue of Scientific Literature is carried on by the Smithsonian Institution by means of a congressional appropriation. The central bureau is in London, where data from regional bureaus are assembled and published in series of annual catalogues. The war has very greatly interfered with this work, some countries being so much in arrears in their contributions toward its support as to necessitate unusually large subscriptions from several institutions.

As its name indicates, the catalogue is made up of bibliographical references to scientific literature in various countries. The United States bureau since 1910 has collected data for this country, aggregating more than 350,000 reference cards. The 17 annual volumes issued in London are sold at an annual subscription price of $85, chiefly to large reference libraries and important scientific institutions, the proceeds covering in part the cost of the publication.

At the international convention in London in 1910 a committee was authorized to secure cooperation with other similar organizations in preparation of the catalogue and to broaden its scope to include technical industries closely allied to researches in pure science. This would not only lead to economy of labor but would provide a uniform reference to the literature of all sciences.

NECROLOGY.

WILLIAM JOEL STONE.

William Joel Stone, A. B., LL. D., United States Senator, regent of the Smithsonian Institution, was born in Madison County, Ky., May 7, 1848, and died April 14, 1918. Mr. Stone was educated at Missouri University, which later conferred upon him the degree of LL. D. He was admitted to the bar in 1869, after which he was successively prosecuting attorney of Vernon County, Mo., Representative in the Forty-ninth, Fiftieth, and Fifty-first Congresses, and governor of Missouri. He was a member of the Democratic National Committee from 1896 to 1904, vice chairman of the committee from 1900 to 1904, and in 1903 was elected to the United States Senate, to which office he was twice reelected. He was regent of the Smithsonian Institution from 1913 until his death.

CHARLES WARREN FAIRBANKS.

Charles Warren Fairbanks, A. B., A. M., LL. D., twenty-sixth Vice President of the United States, regent of the Smithsonian Institution, was born in Union County, Ohio, May 11, 1852; died June 4, 1918. Mr. Fairbanks was educated at Ohio Wesleyan University, was admitted to the Ohio bar.in 1874, and established practice at Indianapolis, Ind. He was delegate and chairman in several national political conventions, United States Senator from Indiana from 1897 to 1905, Vice President of the United States from 1905 to 1909. During his term as Vice President he was ex officio regent of the Smithsonian Institution, and was again regent by resolution of Congress from 1912 until his death.

Respectfully submitted.

CHARLES D. WALCOTT, Secretary.

APPENDIX 1.

REPORT ON THE UNITED STATES NATIONAL MUSEUM.

SIR: Owing to the death on July 16, 1918, of Mr. Richard Rathbun, Assistant Secretary of the Smithsonian Institution in charge of the National Museum, the duty devolves on me of submitting the following report on the operations of the United States National Museum for the fiscal year ending June 30, 1918:

WAR ACTIVITIES.

During the trying conditions that have prevailed in the United States since it entered the war, the National Museum has demonstrated its value as a national asset in many ways. Members of its staff of experts, its great collections, its laboratories, and all the information in its possession, have been placed unreservedly at the service of the executive departments and other Government agencies, and have been freely used by a number of them. Some of its exhibition halls have been closed to visitors and turned into office quarters for one of the important war bureaus of the Government. Facilities for the comfort and recreation of officers and men stationed in the vicinity and drilling on the Mall have been provided in the buildings, and the reading rooms of the libraries have been equipped with tables and writing materials for all men in uniform.

Its department of geology has been frequently called upon to furnish the Bureau of Standards, Naval Experiment Station, Department of Agriculture, Geological Survey, the Carnegie Institution, and various arsenals, materials for experimental work. A single call from the Bureau of Standards embraced 27 varieties of minerals, many of which were rare. To meet all of these demands, it has been necessary to make trips into the field to secure additional supplies. At the request of the National Research Council the head curator of this department has taken over the entire work of securing optical quartz for the needs of the United States and of Great Britain, involving a large volume of correspondence and travel to different points.

The division of mineral technology has concentrated its activities for the year upon the interrelationships, and consequent interdependence, existing in the industries sustained by mineral resources. In addition to instructive exhibits, the curator and his assistants, in the solution of the problems connected with the fertilizer, sulphur, fuel,