In glancing over the somewhat incoherent series of memoirs with which I have endeavoured to illustrate a few of the mental peculiarities of my friend, Mr. Sherlock Holmes, I have been struck by the difficulty which I have experienced in picking out examples which shall in every way answer my purpose. For in those cases in which Holmes has performed some tour-de-force of analytical reasoning, and has demonstrated the value of his peculiar methods of investigation, the facts themselves have often been so slight or so commonplace that I could not feel justified in laying them before the public. On the other hand, it has frequently happened that he has been concerned in some research where the facts have been of the most remarkable and dramatic character, but where the share which he has himself taken in determining their causes has been less pronounced than I, as his biographer, could wish. The small matter which I have chronicled under the heading of “A Study in Scarlet,” and that other later one connected with the loss of the Gloria Scott , may serve as examples of this Scylla and Charybdis which are for ever threatening his historian. It may be that, in the business of which I am now about to write, the part which my friend played is not sufficiently accentuated; and yet the whole train of circumstances is so remarkable that I cannot bring myself to omit it entirely from this series.
I cannot be sure of the exact date, for some of my memoranda upon the matter have been mislaid, but it must have been towards the end of the first year during which Holmes and I shared chambers in Baker Street. It was boisterous October weather, and we had both remained indoors all day, I because I feared with my shaken health to face the keen autumn wind, while he was deep in some of those abstruse chemical investigations which absorbed him utterly as long as he was engaged upon them. Towards evening, however, the breaking of a test-tube