that will be found valuable for everyone concerned with the history of the modern period of philosophy.
Cornell University.
I. This article is a very minute description with many diagrams of an elaborate set of apparatus used for presenting without interruption in small, variable time-intervals a series of visual stimuli, and for accurately recording both the contents and the time of speech-reactions. For this purpose the author employs a combination of phonograph and dictaphone. He presents several pages of Tables showing the calculation of various mechanical factors of operation and their constant errors. In a final paragraph he discusses the theoretical significance of such an elaborate method for psychological purposes and points out that while in the early stages of psychological experimentation the question of technique was overemphasized and the importance of the instruction to the observer was neglected, in the present stage there is a strong tendency for the opposite error, which his method tries to counteract by combining delicacy of apparatus with due consideration of the nature of the instruction (Aufgabe) and of course minute introspection.
II. This is a short reply to some criticisms of Ach's book Über den Wittensakt und das Temperament, by O. Selz, in which Ach points out that he does not hold, as assumed by Selz, that any short or abbreviated act of will must contain all the factors which a complete or most energetic expression of will reveals. Other objections are refuted in Glässner's work (cf. IV).
III. The problem of this investigation was the study of the relation of voluntary effort to continuous mental work. The general method was to present a senseless combination of consonants and vowels of the type "tudap," which the observer first had to read aloud and then to modify aloud by interchanging the first and last consonants, thus reading "pudat." This was continued with many stimuli for ten minutes, once at a slow rate, once moderately fast, and once at a fast speed. The original reading and the identity of the three middle letters favor the perseverative tendency to repeat merely, which had to be overcome by an act of will or strong concentration of attention. The faster speeds increased the obstacle. The apparatus used was the one described by Ach in a previous article (cf. I). Four observers completed three series, one of each speed, on each of six successive days. The time of reading and of the reversed re-reading was measured and a record of errors in both was kept.
