Chapter 13 covered all aspects of Banburismus, but without much of the mathematical and other detail. This chapter seeks to explain depth, Bayes’ theorem, logarithmic scoring (and its application to the Banburies discovered in the roof of Hut 6), decibanning, chains and depth cribbing, comic strips, and twiddling. This seems to be the first publication of much of this explanation. In Chapter 13 I promised a simple illustrative example of depth and some of the terms associated with it. In Table 38.1 QVAJX . . . and the others are three enciphered messages as transmitted. This table does not relate to any particular real-life cipher, and its three enciphered messages are unrealistically short. It illustrates an imaginary system which enciphers letter by letter (as Enigma did), using an enciphering table which would provide hundreds, or more probably thousands, of individual enciphering units, whatever the nature of the imaginary enciphering system. The numbers 180, 181, . . . indicate the positions of the units in the table. The encipherer could choose where in the table to begin enciphering (say, at position 183) and, once started, continued to use the enciphering units in sequence (183, 184, 185, . . .). The legitimate receiver of the message had to be told where to start in the table. This was done by an ‘indicator’, which was itself enciphered, usually by a different system, and formed part of a preamble to the message as transmitted. The three enciphered messages in this example, which may have come from different sources, start at different positions in the enciphering table. They have significant overlaps, and it is where they overlap that they are said to be ‘in depth’. Here the depths are of two messages (as in column 182) or of three (column 183). In real life they could be of ten or twenty. All the letters in a particular column (as QDF in column 183) have been enciphered in exactly the same way.

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The Southeastern Simulation Council met on June 5 at the Redstone Arsenal, Huntsville, Alabama. NASA Simulation Branch and G. E. Analog and Engineering Sub-operation were co-hosts. Attendance was 80 persons.As scheduled, there were three 45-minute papers, all of which were very well received. The first talk was by R. D. Loftin, of the General Electric Huntsville Operation, who presented a tutorial exposition on the fundamentals of random noise theory. This talk paved the way for the succeeding two papers and made them more meaningful. The second paper was presented by Mr. Richard Bryan, of the Georgia Institute of Technology, who talked on Generation of Non-Stationary Stochastic Processes. Among other things, this paper describes a synthesis procedure developed by Dr. Webb of Georgia Technology for the generation of non-stationary noise having prescribed first and second moments. This procedure is an extremely important contribution to the use of analog computers in Monte Carlo studies. The third and final paper of the morning was presented by report on the April meeting of the SCi Board of Directors. Mr. Shaver is the SSC representative to the national board.After lunch at the Officer's Club, the group toured through two facilities of NASA's Simulation Branch. The first tour included a look at a multiple console GPS statistical analog computer and a demonstration of a typical problem solved in this machine. The second tour took the group through the main computer room of the Simulation Branch and included a demonstration of a hybrid simulation study. This hybrid problem-which involved an EAI 231-R, an ADAGE 770 interface, and the ASI 210 digital computer -is concerned with the simulation of a threestage Saturn launch from pad to orbit. We were all much indebted to Fred Shaver and his Simulation Branch personnel for these tours and demonstrations of his equipment. We also greatly appreciated the luncheon arrangement made by Ray Lawrence. EDWARD G. HOLMES: An Optical Computer EDITOR'S NOTE: The following article, based on a presentation at the SSC meeting described in the preceding report, has undergone drastic surgery in the interest of saving it from our Technical Review Board. However, even after its &dquo;matherectomy,&dquo; we believe you will find it interesting-and different.-J.M.With the recent emphasis on optical systems one might expect that sooner or later someone would suggest an optical computer. This really isn't how it happened-and perhaps there were others-but the University of Michigan Research Institute was apparently the first actually producing a practical working instrument. The application was to certain problems suggested by the Air Force and the Army. Later, Conductron Corporation manufactured a similar unit.

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