The Birmingham age-herald., 1923-04-15

been taken from the second Surely in stead of the first, to mislead the solvef Otherwise you would have surely for the first five numbers, which would be too clear an indication. The same reason exists for making A the tenth letter in stead of the eighth; which would reveal the word man The final letter-the e in 'gather'-has been excluded for a req son which will presently explain
 What about the second S-the final letter? Do you not call that recurring letter." asked Marsland, who was closely examining, the table the detective had pre- pared.
 "Not in the crytographic sense It is the first letter of the text repeated after the line had been completed without re- curing letters There is special reason for it's use. The old man has worked on what is called the keyword cipher which is the most difficdlt of all ciphers to dis cover. This system consists of various ar engagements, more or less elaborate, of tables of letters, set down in the form of the multiplication table, and from the table agreed upon messages are constructed whose solution depends on the use of some preconcerted keyword. The most scen- tific adaptation of this principle was con- structed by Admiral Sir Francis Beaufort. In his system the letters of the alphabet are set down one under another from A to Z, then A is added to the line. The next line starts with B and runs to another B at the bottom. You continue till you have the whole alphabet set down in this fash ion. From this table and an agreed key word, which may consist of a proper name or sentence of several words, you con- struct cipher message"
 Howl" asked Marsland, in a tone of keen interest.
 "That is what I now propose to demon- strate to you, if, as I think, the old man constructed his cryptogram in accordance with this principle. l have come to the conclusion that he modified and adapted this system to his own ends, using the letters of the text from the Bible to con- ceal it better, and then made it more diff ficult still by turning the letters into fig ures after. the manner I have described. He has also made slight but not uncom- mon variation from the Beaufort principle by striking out the e in gather, which would follow the 'O' in every letter if the eeAt WdS uoeu OICe, anu SuDSClIuClHS the final s, instead of placing the .S' after e. But the clue that suggested to my mind that he had worked on this principle are the two figures coming together at the top of the circle. In the substituted let ters they form two Ss. Now, why does he have two S's when he carefully avoids recurring letters in the rest of the table? And why did he insert the first s again, as represented by the figure 6, instead of taking the next S in this table?
 "In pondering over these points I dis covered, as l believe, the system of cryp- togram he used to construct his secret He wanted to make the cryptogram difficult of solution, but at the same time he wanted to give some indication of the form of eryptogram he was using when his heirs came to search for the money. The re- curing s indicates that he was working on modification of the system I have explained, in which you add the first let ter of your first column to the bottom, and continue on that system throughout the table. It is not much of a hint, be- cause we have got to find the keyword before we can the table, but by it's help we will start with the assumption that the old man worked on the following table: