“My practice has extended recently to the Continent,” said Holmes, after a while, filling up his old brier-root pipe. “I was consulted last week by François Le Villard, who, as you probably know, has come rather to the front lately in the French detective service. He has all the Celtic power of quick intuition, but he is deficient in the wide range of exact knowledge which is essential to the higher developments of his art. The case was concerned with a will, and possessed some features of interest. I was able to refer him to two parallel cases, the one at Riga in 1857, and the other at St. Louis in 1871, which have suggested to him the true solution. Here is the letter which I had this morning acknowledging my assistance.” He tossed over, as he spoke, a crumpled sheet of foreign notepaper. I glanced my eyes down it, catching a profusion of notes of admiration, with stray “magnifiques,” “coup-de-maîtres,” and “tours-de-force,” all testifying to the ardent admiration of the Frenchman.

“He speaks as a pupil to his master,” said I.

“Oh, he rates my assistance too highly,” said Sherlock Holmes, lightly. “He has considerable gifts himself. He possesses two out of the three qualities necessary for the ideal detective. He has the power of observation and that of deduction. He is only wanting in knowledge; and that may come in time. He is now translating my small works into French.”

“Your works?”

“Oh, didn’t you know?” he cried, laughing. “Yes, I have been guilty of several monographs. They are all upon technical subjects. Here, for example, is one ‘Upon the Distinction between the Ashes of the Various Tobaccoes.’ In it I enumerate a hundred and forty forms of cigar-, cigarette-, and pipe-tobacco, with coloured plates illustrating the difference in the ash. It is a point which is continually turning up in criminal trials, and which is sometimes of supreme importance as a clue. If you can say definitely, for example, that some murder has been done by a man who was smoking an Indian lunkah, it obviously narrows your field of search. To the trained eye there is as much difference between the black ash of a Trichinopoly and the white fluff of bird’s-eye as there is between a cabbage and a potato.”

“You have an extraordinary genius for minutiæ,” I remarked.

“I appreciate their importance. Here is my monograph upon the tracing of footsteps, with some remarks upon the uses of plaster of Paris as a preserver of impresses. Here, too, is a curious little work upon the influence of a trade upon the form of the hand, with lithotypes of the hands of slaters, sailors, corkcutters, compositors, weavers, and diamond-polishers. That is a matter of great practical interest to the scientific detective,—especially in cases of unclaimed bodies, or in discovering the antecedents of criminals. But I weary you with my hobby.”