"Could that tall, dark, nicely-dressed gentleman have been Burchill?" he muttered. "Sounds like him. But you've got a description of Dimambro, at any rate. Now we know of one man who saw the caller at the House of Commons--Mountain, the coachman. Come along--I'll go with you to see Mountain." Mountain, discovered at the mews wherein the Herapath stable was kept, said at once that he remembered the gentleman who had come out of the House of Commons with his late master. But when he came to be taxed with a requirement of details, Mountain's memory proved to be of no real value. The gentleman--well, he was a well-dressed gentleman, and he wore a top hat. But whether the gentleman was dark or fair, elderly or middle-aged, short or medium-heighted, he did not know--exactly. Nevertheless---- "I should know him again, sir, if I was to set eyes on him!" said Mountain, with such belief in his powers. "Pick him out of a thousand, I could!" "Queer how deficient most of our people are in the faculty of observation!" remarked the Professor as he and Selwood left the mews. "It really is most extraordinary that a man like that, with plenty of intelligence, and is no doubt a good man in his own line, can look at another man for a full minute and yet be utterly unable to tell you anything definite about him a month later! No help there, Selwood." It seemed to Selwood that they were face to face with an impossible situation, and he began to feel inclined to share Mr. Halfpenny's pessimistic opinions as to the usefulness of these researches. But Professor Cox-Raythwaite was not to be easily daunted, and he was no sooner baulked in one direction than he hastened to try another. "Now, let's see where we are," he said, as they went round to Portman Square. "We do know for a certainty that Jacob Herapath had a transaction of some sort with one Luigi Dimambro, on November 12th, and that it resulted in his handing, or sending, the said Luigi a cheque for three thousand guineas. Let's see if we can't find some trace of it, or some mention of it, or of previous dealings with Dimambro, amongst Jacob's papers. I suppose we can get access to everything here at the house, and down at the office, too, can't we? The probability is that the transaction with Dimambro was not the first. There must be something, Selwood--memoranda, letters, receipts--must be!" But Selwood shook his head and uttered a dismal groan.