"Thus in the black races the skull is long and narrow, the eye-sockets are long and narrow, and the hair is flat and ribbon-like, and usually coiled up like a watch-spring. In the white races the skull is oval, the eye-sockets are oval, and the hair is slightly flattened or oval in section, and tends to be wavy; while in the yellow or Mongol races, the skull is short and round, the eye-sockets are short and round, and the hair is straight and circular in section. So that we have, in the black races, long skull, long orbits, flat hair; in the white races, oval skull, oval orbits, oval hair; and in the yellow races, round skull, round orbits, round hair.
"Now, in this case we had to deal with a very short round skull. But you cannot argue from races to individuals; there are many short-skulled Englishmen. But when I found, associated with that skull, hairs which were circular in section, it became practically certain that the individual was a Mongol of some kind. The mother-of-pearl dust and the granules of rice starch from the inside of the hat favoured this view, for the pearl-shell industry is specially connected with China and Japan, while starch granules from the hat of an Englishman would probably be wheat starch.
"Then as to the hair: it was, as I mentioned to you, circular in section, and of very large diameter. Now, I have examined many thousands of hairs, and the thickest that I have ever seen came from the heads of Japanese; but the hairs from this hat were as thick as any of them. But the hypothesis that the burglar was a Japanese received confirmation in various ways. Thus, he was short, though strong and active, and the Japanese are the shortest of the Mongol races, and very strong and active.
"Then his remarkable skill in handling the powerful caretaker—a retired police-sergeant—suggested the Japanese art of ju-jitsu, while the nature of the robbery was consistent with the value set by the Japanese on works of art. Finally, the fact that only a particular collection was taken, suggested a special, and probably national, character in the things stolen, while their portability—you will remember that goods of the value of from eight to twelve thousand pounds were taken away in two hand-packages—was much more consistent with Japanese than Chinese works, of which the latter tend rather to be bulky and ponderous. Still, it was nothing but a bare hypothesis until we had seen Futashima—and, indeed, is no more now. I may, after all, be entirely mistaken."
He was not, however; and at this moment there reposes in my drawing-room an ancient netsuke, which came as a thank-offering from Mr. Isaac Löwe on the recovery of the booty from a back room in No. 13, Birket Street, Limehouse. The treasure, of course, was given in the first place to Thorndyke, but transferred by him to my wife on the pretence that but for my suggestion of shell-dust the robber would never have been traced. Which is, on the face of it, preposterous.
IV
THE BLUE SEQUIN
Thorndyke stood looking up and down the platform with anxiety that increased as the time drew near for the departure of the train.