RESEARCHES IN PRACTICE AND HABIT, BY W. Smythe Johnson. I. Triangular movement. The subject was required to tap continuously at the corners of an equilat¬ eral triangle whose sides measured 2o0m. This triangle was formed by a special triangular contact key, Fig. i, with knobs 2o0m from each other. This key was originally constructed at Dr. Scripture’s suggestion for use in testing school-children by Gilbert, by whom, however, it was used merely for tapping and not as a habit-key.1 The key was placed in circuit with a 4 ampère battery and the pri¬ mary coil of a spark coil, the con¬ denser being connected around the break. From the poles of the sec¬ ondary coil, one wire led to the base of the recording drum, the other to the base of a ioo v.d. electric fork bearing a flexible point on one of its prongs. Pressure on one of the key-knobs closed the primary circuit for an instant. When the circuit was broken a spark passed through the smoked paper on the surface of the drum making a dot on the time line drawn by the fork. Each spark thus indicated a tap on one of the three key-knobs. The time between the sparks could be read to the thousandth of a second.2 The subjects included : K. (Kochi) and M. (Matsumoto), who were Japanese students of psychology ; P. (Powell), a student of English ; 1 Gilbert, Researches on the mental and physical development of school-children, Stud. Yale Psych. Lab., 1894 II 40 (especially p. 40 and Fig. 5). 2 The arrangement of the recording apparatus was identical with that of Exercise IX in Scripture, Elementary course in psychological measurements, Stud. Yale Psych. Lab., 1896 IV 113 ; it is shown in Scripture, New Psychology, frontispiece, London 1897.