For help in causing this desire to come to fruition, I should like to express my indebtedness especially to Professor (then Commander, U.S.N.R.) Howard H. Aiken of Harvard University, whose stimulus, while I was stationed for ten months in 1945-46 in his laboratory, was very great. I should also like to express my appreciation to Mr. Harry J. Volk, whose vision and enthusiasm greatly encouraged me in the writing of this book. For careful reviews and helpful comments on the chapters dealing with existing mechanical brains, I am especially grateful to Dr. Franz L. Alt, Mr. E. G. Andrews, Professor Samuel H. Caldwell, Dr. Grace M. Hopper, Mr. Theodore A. Kalin, and Dr. John W. Mauchly, who are experts in their fields. Dr. Ruth P. Berkeley, Dr. Rudolf Flesch, Mr. J. Ross Macdonald, Dr. Z. I. Mosesson, Mr. Irving Rosenthal, Mr. Max S. Weinstein, and many others have been true friends in reading and commenting upon many parts of the manuscript. Mr. Frank W. Keller devoted much time and skill to converting my rough sketches into illustrations. Mr. Murray B. Ritterman has been of invaluable help in preparing and checking much of the bibliography. Miss Marjorie L. Black has helped very greatly in turning scraps of paper bearing sentences into an excellent manuscript for the printer. For permission to use the quotations on various pages in Chapters 11 and 12, I am indebted to the kindness of: E. P. Dutton & Co., for quotations from _Frankenstein_, by Mary W. Shelley, Everyman’s Library, No. 616. Samuel French, for quotations from _R. U. R._, by Karel Čapek.[1] _Modern Industry_, for a quotation from the issue of February 15, 1947. [1] Copyright 1923 by Doubleday, Page and Co.; all rights reserved; quotations reprinted by permission of Karel Čapek and Samuel French. Responsibility for the statements and opinions expressed in this book is solely my own. These statements and opinions do not necessarily represent the views of any organization with which I may be or have been associated. To the best of my knowledge and belief no information contained in this book is classified by the Department of Defense of the United States. EDMUND CALLIS BERKELEY CONTENTS 1. CAN MACHINES THINK? What Is a Mechanical Brain? 1 2. LANGUAGES: Systems for Handling Information 10 3. A MACHINE THAT WILL THINK: The Design of a Very Simple Mechanical Brain 22 4. COUNTING HOLES: Punch-Card Calculating Machines 42 5. MEASURING: Massachusetts Institute of Technology’s Differential Analyzer No. 2 65 6. ACCURACY TO 23 DIGITS: Harvard’s IBM Automatic Sequence-Controlled Calculator 89