Accordingly Temistocle was watched instead of his master. It was found that he frequented the society of other Neapolitans, and especially that he was in the habit of going from time to time to the Ripa Grande, the port of the Tiber, where he seemed to have numerous acquaintances among the Neapolitan boatmen who constantly came up the coast in their "martingane"--heavy, sea-going, lateen-rigged vessels, bringing cargoes of oranges and lemons to the Roman market. The mystery was now solved. One day Temistocle was actually seen giving a letter into the hands of a huge fellow in a red woollen cap. The _sbirro_ who saw him do it marked the sailor and his vessel, and never lost sight of him till he hoisted his jib and floated away down stream. Then the spy took horse and galloped down to Fiumicino, where he waited for the little vessel, boarded her from a boat, escorted by a couple of gendarmes, and had no difficulty in taking the letter from the terrified seaman, who was glad enough to escape without detention. During the next fortnight several letters were stopped in this way, carried by different sailors, and the whole correspondence went straight to the Cardinal. It was not often that he troubled himself to play the detective in person, but when he did so, he was not easily baffled. And now he observed that about a week after the interception of the first letter the small drafts which used to come so frequently to Del Ferice's address from Florence suddenly ceased, proving beyond a doubt that each letter was paid for according to its value so soon as it was received.