This is more properly an announcement of this title, since this word and diagram description of mechanical brains is too technical for us to assess. This tells of the various new machines which have been developed by the laboratories, the principles involved, their reliability, and their functions and limitations. These machines can calculate, remember, reason, store information, select and handle information and there is additional material on the new truth-calculators, robots, etc., which will be of great value in science and industry. This is of course for the scientifically initiated reader.