K. Pearson 
the scale may be found in the fact that the plotted points of the regression curves 
are for a number of pairs of characters, within the limits of random sampling, on 
a straight line when such a scale of intelligence is used. It is convenient to 
put the plotted values of the physical character in each case along the centroid 
value of the frequency of the corresponding grade. 
In the Cambridge graduates the median ability lies fairly closely on the 
boundary between third class honours and pass degrees. In the school children 
the median division is closely in girls, and less closely but still approximately in 
boys, between the intelligent and slow intelligent groups. The following, indeed, 
will be found to give roughly the equivalent grading : 
School Children Graduates 
Quick Intelligent = First Class Honours. 
Second Class Honours. 
Intelligent •■• =\ ■ t r^^ TT 
° I Third Class Honours. 
Slow Intelligent! 
Slow ... 
Slow Dull 
Very Dull 
= Pass Degrees. 
This equivalence of grouping is a fairly satisfactory result, but it suggests that, 
in future, it would be better to break up the intelligent class into two sub-groups, 
and to differentiate further those who take pass degrees. We might tlien form the 
following scale of intelligence : 
(a) Specially Able, (^) Capable, (7) Intelligent, (S) Slow Intelligent, (e) Slow, 
(f) Slow Dull, (17) Very Dull and Mentally Defective. The first three groups 
would then correspond approximately to first, second, and third class school and 
University honours*. 
* To the teacher trained by many generations of pupils these divisions will provide almost uncon- 
sciously an api^reciation of classes. For tliose wlio have not this experience it is difficult hnt necessary 
to attempt a verbal description. Tlic following definitions are based on those provided in tliu schedules 
for the inquiry as to school children, and for a further research on adults in progress. 
(a) Specially Able: a mind especially briglit and quick both in perception and reasoning about 
not only customary but novel facts. Able and accustomed to reason rightly about things on pure self- 
initiative. 
{|8) Capable : a mind less likely than the specially able to originate inquiry, but quick in perception 
and in reasoning rightly about the perceived. 
(7) Intelligent : a mind ready to grasp and capable of perceiving facts in most fields. Capable of 
good reasoning with a moderate effort. 
(5) Sloio Intelligent : a mind slow generally, although possibly more rapid in certain fields, but 
quite sure of knowledge once acquired. 
(e) Sloiv : a mind advancing in general, but very slowly ; with time and consideral)le effort not 
incapable of progress. 
(f) Slow Dull: a mind capable of perceiving relationship between facts in some few fields with long 
and continuous effort, but not generally, or without external aid. 
(•))) Very Dull: a mind capable of holding only the simplest facts, and incapable of grasping or 
reasoning about the relationship between facts ; the very dull group covers but extends somewhat further 
up than the mentally defective. 
14—2 
