A B C D E F G H I K L M N O P Q R S T U V W X Y Z A 3 1 4 1 1 B 3 2 3 1 1 4 1 3 1 1 C 1 1 D 2 2 1 E 1 5 1 F 1 2 1 1 1 G 1 1 1 1 H 5 1 3 I 1 1 5 1 K 1 2 1 L 8 1 M 1 1 N 1 1 2 1 2 1 O 6 1 4 1 P 2 1 2 3 Q 2 R 1 2 2 7 2 1 S 2 2 1 T 1 2 1 U 1 3 1 V 2 W 2 X 1 5 1 4 1 1 3 2 1 1 Y 5 1 Z 2 1 2 From this table we pick out the letters B, E, F, O, R, T, X, as tentative letters of the key word on account of the variety of other letters with which they occur. As there are but two vowels for seven letters, we will add A to the list on account of its occurrences with B, D, E, R, and X. This leaves the letters for the bottom lines of the square as follows: +----+----+----+----+----+ | . | . | . | . | . | +----+----+----+----+----+ | . | . | . | C | D | +----+----+----+----+----+ | G | H | IJ| K | L | +----+----+----+----+----+ | M | N | P | Q | S | +----+----+----+----+----+ | U | V | W | Y | Z | +----+----+----+----+----+ Referring to the table again we find the most frequent combination to be EL, occurring 8 times, with no occurrence of LE. Now, TH is the commonest pair in plain text, and HT is not common. The fact that H occurs in the same horizontal line with L and that E and T are probably in the key, will lead us to put E in the first line over H and T in the first line over L, so as to make EL equal TH.