F. C. C. Hansen and Alfred Lehmann, Danish psychologists, in 1895 published a pamphlet of 60 pages entitled _Über Unwillkürliches Flüstern_ (_On Involuntary Whispering_). This brochure reported experiments by the authors which, they claimed, showed that the apparent success in telepathic transmissions of numbers achieved under the control of representatives of the S. P. R. and published in its _Proceedings_ (Vols. VI and VIII) might not have been due to telepathy, but to involuntary whispering with closed lips. Messrs. Hansen and Lehmann sat between concave spherical mirrors so that the concentration of sound, their heads occupying the foci, would presumably be an equivalent for the hyperaesthesia of a _hypnotized_ “percipient.” Each in turn acted as agent, to see if figures could be conveyed by “involuntary whispering,” and seemed to have a large degree of success. How it is possible to test whether audible whispering can be produced with closed lips and do so without the exercise of volition is something of a mystery. And how they could be certain that some factor of telepathy did not enter into their own experiments is not clear.[26] But Professor Sidgwick, who five years before Hansen and Lehmann’s pamphlet had considered and discussed the possibility of “unconscious whispering,”[27] later instituted experiments of his own and concluded that something in this direction was possible. But he, William James and others thoroughly riddled the Hansen and Lehmann dream that perhaps they had explained the published S. P. R. series of experiments for the transfer of numbers. For one thing, a part of the experiments had been with the parties in different rooms. And the notion that when the voluntarily involuntary whisper[28] of a digit was misheard, a digit whose name somewhat resembled was most likely to be selected by the agent, was riddled too, so far as it applied to the English experiments. The Danish gentlemen had never claimed that their explanatory theory was proved, but only that it was probable. Later they quite frankly acknowledged that the Sidgwick and James “experiments and computations” had weakened even its probability. Since their pamphlet had attracted much and widespread interest, as it deserved to do, and since if they could establish or even strengthen the probability of their theory it would mean a restoration and enhancement of their prestige, set back by the counter-strokes of Sidgwick, James, Schiller and others, it would seem that the inducement not to stop short, but to go on with the experimentation would be almost irresistible. But they either did stop there or their results were disappointing, for nothing more, so far as I can learn, was ever heard from them on this subject.