Here he saw at a glance that the same thing obtained, the pounds alone, and the pence and shillings added together, making two similar pairs, and therefore presumably standing for the same word.
This discovery restored all his eager interest. It seemed definitely to prove three things, each several one of which afforded him the liveliest satisfaction. First, these combinations of figures proved that there really was some underlying scheme, and that in its turn involved the hidden message; secondly, they showed that he, French, was on the direct road towards a solution; and thirdly, they indicated a code or cipher built up of pairs of numbers, a frequent combination, embracing many well-known varieties of cryptogram.
His next step was, therefore, to rewrite the list in dual column, the pounds in front, the pence and shillings added together behind. This gave him a new jumping-off place in the following:
328—6
568—5
1039—4
936—9
713—11, and so on.
On this he started his three men, making them try to work out keys on squares and parallelograms, as well as in other well-established ways. Then the pounds figure proving too large for this, he tried adding the various digits of these figures together. In this way, 328 became 3+2+8 or 13, and so he compiled a second list beginning:
13—6