Page:Mind (Old Series) Volume 11.djvu/67

 56 G. S. HALL AND J. JASTROW : those that seemed exceptionally long or otherwise unfavourable re- jected by the counter, the conditions were favourable. Yet even here for the longer slips of between twenty or thirty spots the average time per spot was rarely reduced below sec. and sometimes reached and even exceeded ^. The strain of con- centration is great. The attention is very prone to slip forward or backward one or two steps or to lose the place along the line of such uniform spots even if they are 1 cm. apart and only 1 ft. from the eye, and rests must be frequent and of increasing length. By arbitrarily varying the rhythm, i.e. by counting by ones or in groups of twos, threes, fours, &c., the time-results can be varied constantly, as will be seen later in the full report, but very rarely reduced below the limit. APPARATUS. ipolgld I o gl b d p i B For the further study of these and other rhythmic phenomena, undertaken with Mr. Joseph Jastrow, two round plates of solid brass, 17 cm. in diameter and 4 mm. thick, were fastened 2 cm. apart and clamped by a screw on the upright revolving shaft