It was on one of those delightful evenings for which our English summer is famous, that HOLES and I were as usual sitting together and conversing as to the best methods of inferring an Archbishop from a hat-band and a Commander-in-Chief from a penny-whistle. I had put forward several plans which appeared to me to be satisfactory, but HOLES had scouted them one after another with a cold impassivity which had not failed to impress me, accustomed though I was to the great man's exhibition of it. "Here," said HOLES, eventually, "are the necessary steps. Hat-band, band-master, master-mind, mind-your-eye, eye-ball, ball-bearing, bear-leader, Leda and the Swan, swan-bill, bill-post, post-cart, cart-road, roadway, Weybridge, bridge-arch, arch-bishop. The inference of a Commander-in-Chief is even easier. You have only to assume that a penny-whistle has been found lying on the Horse-Guards' Parade by the Colonel of the Scots Guards, and carried by him to the office of the Secretary of State for War. Thereupon you subdivide the number of drummer-boys in a regiment of Goorkhas by the capital value of a sergeant's retiring pension, and----" But the rest of this marvellous piece of concise reasoning must remain for ever a secret, for at this moment a bugle-call disturbed the stillness of the summer night, and HOLES immediately paused. "What can that mean?" I asked, in some alarm, for Camberwell (our meeting place) is an essentially unmilitary district, and I could not account for this strange and awe-inspiring musical demonstration. "Hush," said HOLES, with perfect composure; "it is the agreed signal. Listen. The great Samovar diamond, the most brilliant jewel in the turquoise crown of Hungary, has been lost. The Emperor of AUSTRIA is in despair. Next week he is due at Pesth, but he cannot appear before the fierce and haughty Magyars in a crown deprived of the decoration that all Hungary looks upon as symbolical of the national existence. A riot in Pesth at this moment would shake the Austro-Hungarian empire to its foundations. With it the Triple Alliance would crumble into dust, and the peace of Europe would not be worth an hour's purchase. It is, therefore, imperative that before the dawn of next Monday the diamond should be restored to its wonted setting." "My dear HOLES," I said, "this is more terrible than I thought. Have they appealed to you, as usual, after exhausting all the native talent?" "My dear POTSON," replied my friend, "you ask too much. Let it suffice that I have been consulted, and that the determination of the question of peace or war lies in these hands." And with these words the arch-detective spread before my eyes those long, sinewy, and meditative fingers which had so often excited my admiration.