A faded cretonne curtain hid an inner and probably a smaller room where the elder of the men slept. They sat on either side of a table, a kerosene lamp placed exactly in the centre supplying light for their various occupations. The elder of the two was bent forward over a microscope, his big hands adjusting the focus screw. Presently he would break off his work of observation and jot down a few notes in crabbed German characters. His big head, his squat body, his long ungainly arms, his pale face with its little wisp of beard, would have been recognized by Oliva Cresswell, for this was Professor Heyler--"the Herr Professor," as Beale called him. The man sitting opposite was cast in a different mould. He was tall, spare, almost aesthetic. The clean-shaven face, the well-moulded nose and chin hinted at a refinement which his shabby threadbare suit and his collarless shirt freakishly accentuated. Now and again he would raise his deep-set eyes from the book he was reading, survey the absorbed professor with a speculative glance and then return to his reading. They had sat in silence for the greater part of an hour, when Beale's tap on the door brought the reader round with narrow eyes. "Expecting a visitor, professor?" he asked in German. "Nein, nein," rambled the old man, "who shall visit me? Ah yes"--he tapped his fat forefinger--"I remember, the Fraeulein was to call." He got up and, shuffling to the door, slipped back the bolt and turned it. His face fell when he saw Beale, and the man at the table rose. "Hope I am not disturbing you," said the detective. "I thought you lived alone." He, too, spoke in the language which the professor understood best. "That is a friend of mine," said old Heyler uncomfortably, "we live together. I did not think you knew my address." "Introduce me," said the man at the table coolly. The old professor looked dubiously from one to the other. "It is my friend, Herr Homo." "Herr Homo," repeated Beale, offering his hand, "my name is Beale." Homo shot a keen glance at him. "A split! or my criminal instincts fail me," he said, pleasantly enough. "Split?" repeated Beale, puzzled. "American I gather from your accent," said Mr. Homo; "pray sit down. 'Split' is the phrase employed by the criminal classes to describe a gentleman who in your country is known as a 'fly cop'!" "Oh, a detective," smiled Beale. "No, in the sense you mean I am not a detective. At any rate, I have not come on business." "So I gather," said the other, seating himself, "or you would have brought one of the 'busy fellows' with you. Here again you must pardon the slang but we call the detective the 'busy fellow' to distinguish him from the 'flattie,' who is the regular cop. Unless you should be under any misapprehension, Mr. Beale, it is my duty to tell you that I am a representative of the criminal classes, a fact which our learned friend," he nodded toward the distressed professor, "never ceases to deplore," and he smiled blandly.