130	THE  FACTORS OF THE  MIND
every child in a given school (157 in all). The method of * incom-
plete paired comparison' was followed. The specimens were first
roughly grouped and ranked; and more or less similar pairs were
then submitted to 63 students and teachers. They were first asked :
is this specimen of greater, less, or equal merit than that ? Merit
was defined as ' legibility, i.e. ease and comfort in reading/ If
more than 40 observers gave the same answer, the judgment was
held to be * significant/ and the group was said to agree. Thus (so
it was eventually claimed) the group * agreed ^? that the entire ^l
'field' of 157 specimens could be arranged in an asymmetrical,
transitive series, such that every specimen was either of greater,
lesser, or equal merit as compared with any other; and the same for
the differences. On this basis a final order was drawn up, proceed-
ing, where possible, by ' just perceptible gradations '; and the
specimens were numbered on a decimal system, o-i, 0-2, . . . 0*9,
i-o, . . . etc. The ' sum' of two intervals, say (8-0 — 7-0) -|-
(7-0' — 6-0), was then defined as the interval between the extremes,
viz. (8-0 — 6-0), where 7-0 and 7*0' do not necessarily denote the
same specimen, but only specimens having the same number and
therefore indistinguishable in merit.
With this definition the following postulates were verified, for a
significant majority of the 63 observers. For simplicity 1 formulate
each postulate in terms of a concrete instance.^2
(i) Postulate of Uniqueness.—Taking any equivalent pairs from
the series of 157, it was found that the operation of adding any two
discrimination of certain individuals seemed to make the notion of a series,
which would be linear for all, an entirely hopeless quest. For this reason,
except when the inter-personal correlations are high, 1 prefer scales and
schemes of marking based on the assumption of a normal distribution, rather
than a rectilinear. Dewar [118] and Eysenck (unpublished thesis) have both
taken up the same question in turn, and have come to the same conclusion,
^1	Owing to lack of time, systematic comparisons with all the 157 specimens
and all the original 63 observers were not actually carried out,   A * sub-
sample ' of the ^£ sample field ' was used instead.    This unfortunately makes
it impossible to give any clear estimate of the reliability of the final con-
clusions.   Woods and Winter similarly attempted to construct a linear series
with children's compositions; and quite recently E, M. John has taken up
the same problem with artificially constructed prose passages.
^2	If the reader desires to test them for himself with actual specimens, I
suggest that he take the examples of handwriting and drawing given in the
L.C,C. Report already cited ([41], pp. 371-98), and treat the numerals in the
text as the age-labels*   (The first postulate cannot be tested, unless the reader
can provide himself with equivalent specimens, since only one is printed for
each age.)