In the acquisition of objects visualizing the history of electric light the Museum has been rather fortunate, particularly as regards the developments in the United States. Thus mention may be made of the original Patent Office models of the more important dynamos, arc lights and incandescent lights, together with original commercial apparatus after these models; a unit of the equipment used in the first commercially successful installation on land of an incandescent lighting system, presented by Joseph E. Hinds in whose engraving establishment in New York City the installation was made in 1881; and a large series of incandescent lights, mainly originals, visualizing chronologically the developments of the Edison light from its inception, presented at intervals since the year 1898 by the General Electric Company. The object of all collections in the Divisions is to visualize broadly the steps by which advances have been made in each field of engineering; to show the layman the fundamental and general principles which are the basis for the developments; and to familiarize the engineer with branches of engineering other than his own. Normally when a subject is completely covered by a collection of objects, a paper is prepared and published describing the collection and the story it portrays. In the present instance, however, on account of the uncertainty of the time of completing the collection, if it is possible ever to bring this about, it was thought advisable to publish Mr. Schroeder’s paper which draws upon the Museum collection as completely as possible. CARL W. MITMAN, ~Curator, Divisions of Mineral and Mechanical Technology, U. S. National Museum~. CHRONOLOGY OF ELECTRIC LIGHT 1800--Allesandro Volta demonstrated his discovery that electricity can be generated by chemical means. The VOLT, the unit of electric pressure, is named in his honor for this discovery of the electric battery. 1802--Sir Humphry Davy demonstrated that electric current can heat carbon and strips of metal to incandescence and give light. 1809--Sir Humphry Davy demonstrated that current will give a brilliant flame between the ends of two carbon pencils which are first allowed to touch each other and then pulled apart. This light he called the “arc” on account of its arch shape. 1820--André Marie Ampère discovered that current flowing through a coiled wire gives it the properties of a magnet. The AMPERE, the unit of flow of electric current, is named in his honor for this discovery.