191112.] A Method of Measuring Mental Processes. 85 
Ten cases were depressed (Cases 3, 13, 15, 16, 19, 20, 21, 26, 27 and 
29). Their maximum output was 312, 1075, 364, 930, 1122, 276, 520, 
812, 656 and 400 respectively. Their average was 646 and was 41 -6 
below the normal. The degree of excitement or depression was in no 
case severe. 
The rest of the patients (Cases 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 17, 23, 
24, 25, 30) were enjoying a normal interlude. Their average was 598, and 
was 45 ‘9 below the normal. Among them the lowest recorded was in Case 
30, who reached the remarkably low output of 219 : the highest, 1030. 
Even the apparently normal intervals in cases of maniac depressive insanity 
therefore but rarely indicate a normal mental working capacity. 
Unlike the normal cases, the maximum was not always attained on the 
fifth day. In Case 30 the maximum was reached on the second day ; 
“ habituation ” and exercise on the subsequent days were insufficient to 
ensure further increase, and a diminution in the output occurred. The 
cases were divisible into three groups, according to the day on which the 
maximum output occurred. In Group A — Cases 5, 15 and 29 — the 
maximum was attained on the third day; in Group B — Cases 1, 2, 6, 8, 10, 
12, 14 and 25 — the maximum was reached on the fourth day; and in 
Group C — the remaining eighteen cases — the maximum was achieved on 
the fifth day. 
In Group A the maximum mental working capacity varied from 364 to 
674 units, and the average was 479, i.e. 628 (43 per cent.) below the 
normal. 
In Group B the lowest maximum total recorded was 130, the highest 
809 ; four were below 500 ; the average of the eight cases in this group 
was 488, which was 619 (55 per cent.) below the normal. 
In Group C the smallest amount of work was done by Case 20 — 276 
units; the largest by Case 19 — 1122 units: five cases, 9, 11, 13, 16 and 19, 
varied between 930 and 1122; they therefore showed practically the 
average normal mental working capacity : four produced less than 400 units, 
five less than 500, seven less than 600, nine less than 700, eleven less than 
800, and thirteen less than 900. The average of all was 692, which was 
415 (37 per cent.) lower than the normal. 
Improvability. 
In Group C the percentage improvement between the first and the fifth 
days was remarkably high : it varied from 41 (Case 22) to 153 (Case 24). 
Only three showed less than 50 per cent, improvement ; six showed over 
100 per cent. ; the average improvement of the eighteen cases in this group 
