The history of the transistor begins with the decision to study intensively the properties of silicon and germanium. This decision was made in 1946 as a result of a series of conferences intended to establish a plan for semiconductor research, which was then being resumed after a war-time lapse. Although silicon and germanium were the simplest semiconductors, and most of their properties could be well understood in terms of existing theory, there were still a number of matters not completely investigated. It was also thought wise to develop techniques with these well-known substances before experimenting with a wider variety of materials. The plan was thus directed definitely toward establishing fundamental understanding of phenomena and proper experimental techniques and not toward the solution of problems of technological rather than scientific importance. Work was begun actively in January 1946 under the direction of W. Shockley. J. Bardeen worked on the theory, G. L. Pearson conducted the experiments on bulk properties, and W. H. Brattain those on surface properties. This work was aided by results obtained by J. H. Scaff and H. C. Theuerer during the war, as well as those obtained by other laboratories. From the point of view of the communications art, it appeared that the most important development likely to arise from semiconductor research, and quite possibly from any branch of solid-state research, would be a useful semiconductor amplifier. This consideration influenced the emphasis of the work in various parts of the solid-state area . Very early in the program it was predicted by Shockley from the existing theories for silicon and germanium that appreciable resistance modulation of thin layers of semiconductor could be produced by inducing a net charge on them with a strong electric field. This proposed form of modulation, which became known as the “ field effect, ” was electronic, rather than thermal as in the case of a thermistor, and it appeared that it might lead to new and useful semiconductor amplifiers. Since the then-hypothetical field effect did not violate any of the basic laws of nature, it constituted a theoretical “ existence proof” of an electronic