are more specifically those of self-consciousness have been treated by him with a curtness and an inadequacy wholly unworthy of his own skill and experience. The result is that he almost wholly abandons the only region where, despite our limitations, we finite beings have the least comprehensible indication, the least concrete and reasonably intelligible exemplification, of how one individual system can "bring home" and "suppress" and yet "keep" its own particulars. The consequence is—the metaphors aforesaid, and the almost pathetically inadequate conclusion of a magnificently begun and in part most admirably conducted enterprise, where learning, dialectical skill, depth, ingenuity, and delight in the spirit of free inquiry, have conspired to make many of the chapters almost classical in their excellence, while the whole book remains so fragmentary in its impression.
The material for this treatise on the Perception of Small Differences was derived from a large number of experiments on the extent, time, and force of movement with the arm, on lifted weights and on lights. Under most of these divisions experiments were made according to four psychophysical methods, and commonly with several subjects,—the object being less to establish a 'law' than to investigate the mutual relations of the psychophysical methods, the value and meaning of variable and constant errors, the effects of practice, and "the significance of the confidence of the experimentee in relation to objective correctness."
As regards the psychophysical methods, the authors find the method of just observable difference unsatisfactory, the method of right and wrong cases the most accurate, and the method of average error the most convenient of all the methods. Merkel's method of doubled stimuli, and the method of mean gradations, classed together under the heading, "method of estimated amount of differences," give variable results, and the authors conclude that in these methods the "observer probably does not estimate quantitative relations in sensation, but quantitative differences in the stimuli learned by association" (p. 152). The experiments leave no doubt in regard to the faultiness of the method of j. o. d.; the results contradict each other and the results gained from other methods. At the same time,
