istics of the operator and give 'personal quality' to the work itself. About twenty-five years ago, being much interested in problems of this kind (more than at the present moment), I spent many 'odd' and generally otherwise unusable quarter and half hours in pitching a stick into the air and noting whether it fell across any of a series of parallel lines drawn on a plane surface upon which it dropped. This cheerful occupation was continued until the stick had been thrown 20,000 times, and then the number of times it had fallen upon a line was compared with the number indicated by theory. It so happens that according to theory this experiment ought to determine the value of that important constant, the ratio of the circumference to the diameter of a circle, and in the present instance it promised for a time to do this in a most satisfactory manner. Indeed at the end of about 12,000 throws the value of 'π' was determined correctly to three decimal places and nearly correctly in the fourth. But from this time on the graphically constructed line of the experiment began to depart very slightly but very persistently from the line of theory and continued to do so to the end. The explanation was easy, it being evident that the operation which was intended to be purely mechanical was not so. There was present an unconscious personal element which interfered with the regularity of the work, to a very minute degree, it is true, but the effect of which became manifest when the run teas long. The deviation was due to a, perhaps, very rarely occurring error of judgment in determining a single fact of the experiment, but in the long run these errors leaned towards one side, and this was beautifully revealed in the graphic exhibit of the whole series. I do not recommend the process as a means of determining errors of this kind, for it is altogether too laborious, and besides, I have not found it necessary, kind friends having generally kept me well informed as to my errors in judgment. What I want to illustrate and emphasize is the importance of my being unconscious of this bias, which otherwise would have destroyed the value of the whole experiment. It is the 'unconscious touch' which most surely identifies personality in any artistic performance. It is likely that Raphael never meant to paint two Madonnas alike, indeed it is likely that he would generally make some effort to have each different from all that he had done before, but all have something in common, unsuspected by the artist but known to the expert and furnishing a practically sure means of identification. Moreover, these unconscious technicalities of an artist, the key to identification, are most frequently known and utilized by persons who have little knowledge and less appreciation of the real artistic qualities of the works which they compare (see Ruskin on the identification of old masters), the operation being the more certain as it is more purely mechanical. It is within the memory of most of those who will read this that the result of a national election together with the whole character and policy of the national government narrowly escaped being determined by the skillful introduction of a single phrase of only three words into a letter which afterwards proved to be a forgery. So characteristic of the alleged author was this phrase that at first even those who knew him best were reluctant to deny its authenticity. And yet I have excellent reasons for believing that the distinguished statesman whose splendid career was thus imperilled was entirely unconscious of the uncommon frequency with which this phrase occurred in his speaking and in his writing. It is because the scheme of the 'characteristic curve' lends itself to the development in a purely mechanical way of idiosyncrasies of which the author must be unconscious that it is thought to have some value as a means of identification. It may be that this as-
