He would then cut up désire and dirige into the syllables de-si-re and di-ri-ge, for each of which the syllabary had set figures; there were also arbitrary numbers for sur, de, and que. So the whole sentence would take up only fourteen numbers when written out.
It would seem at first sight that to interpret such a dispatch would be a perfectly hopeless task, to any one who had not the key to the cipher before him. That the admirably patient and ingenious Scovell at last made out for himself a key from the laborious comparison of documents, was nevertheless the fact. He was started on the track by the fortunate circumstance that most of the intercepted dispatches were only partly in cipher. Marmont would write
‘Avec les moyens que j’ai, et 798, 1118, 602, 131, 1112.663.1135.502 au delà de Sabugal,’
or
‘J’avais donné l’ordre que 1003, 497, 1115, 1383, 69,711, 772, 530, de descendre cette rivière et de se mettre en communication avec moi.’
Clearly the cipher-figures in the first case have something to do with a march on Sabugal, in the second with orders to some general or body of troops (to be identified hereafter) to march down a river which the context shows must be the Tagus. This is not much help, and the task looked still very hopeless. But when intercepted dispatches accumulated in quantities, and the same cipher-figures kept occurring among sentences of which part was written out in full, it became evident that various cryptic figures must mean places and persons who could be guessed at, with practical certainty. Occasionally a French writer completely ‘gives himself away’ by carelessness: e.g. Dorsenne wrote on April 16 to Jourdan,
‘Vous voulez de renseignement sur la situation militaire et administrative de 1238:’
obviously the probable interpretation of this number is ‘the Army of the North,’ and this is rendered almost certain by passages lower down the same letter. Equally incautious is King Joseph when he writes to Marmont,
‘J’ai donné l’ordre au général Treillard de 117.8.7 la vallée du 1383, afin de marcher à 498.’
Considering the situation of the moment 117.8.7 must almost certainly mean evacuate, 1383 Tagus, and 498 some large town.[798] [The particular dispatch in which this occurs is on a most curious piece of paper, half an inch broad, a foot long, and excessively thin. It is bent into twelve folds, and would fit into any small receptacle of one inch by half an inch. I fear the bearer who had it on his person must have come to a bad end.] Suchet also made Scovell the present of some useful words when he wrote on September 17 to Soult,