FEBRUARY 9, 1912] 
exact size, form and weight of every living 
plant, the rate of growth of each and every 
leaf, root, flower and fruit, the absorption 
rate for each and every chemical element 
drawn from the soil, the rate of increase 
in tensile strength, the deposit of chloro- 
phyl, the internal structure of each and 
every cell, ete., ad infinitum. The possibil- 
ity of measurement is here practically un- 
limited. An adequate measure is, however, 
not a complete measure, but one which 
answers a purpose. The gardener meas- 
ures the specific thing which he wants to 
know. 
Now, the human psycho-physical organ- 
ism is at least as rich and as varied as a 
well-cultivated garden, if we may make so 
erude a comparison. While mental meas- 
urements are not developed to the same de- 
eree of precision as those of the gardener, 
they are nevertheless possible and may be 
quite as serviceable. The question is not 
how many measures are possible. No sane 
individual would ever undertake to make 
all possible measurements on a singer. 
The question is this: Can we command 
measurements which shall answer our pres- 
ent purpose? In the present case, do these 
measurements give us an adequate esti- 
mate of the various capacities and qualifi- 
eations of this individual as a singer? 
The list here given is therefore not an at- 
tempt to show how many can be made, but 
to suggest which of those available may 
answer our purpose, and, when taken to- 
gether, prove an adequate measure. 
In the way of mental measurements, we 
can get practically what we want, provided 
we are willing to deal with specific facts. 
Our present list makes a formidable array, 
yet it is limited to those for which I, though 
not an expert in this field, know meth- 
ods and means of measurement, and to 
such as are essential to a reasonably repre- 
sentative survey of the matters to which 
SCIENCE 
209 
they pertain; and measurements which 
would result if any given point were fol- 
lowed up intensively are not mentioned. 
To the extent that they are representative 
and no essential feature is overlooked, they 
constitute an adequate measure of an in- 
dividual as a singer. 
There is a continual warfare between 
psychology, as a science, and the demands 
in practical life for a single general meas- 
ure for some practical purpose. Much 
work has been done on the naive assump- 
tion that a single measure of a cognitive 
capacity should serve as a general measure 
of intelligence. Space discrimination, re- 
action after choice, the memory span, and 
such specific cognitive measures have been 
used in seeking correlations with some sort 
of generally recognized intelligence, but of 
course in vain. For psychology demands 
that each measurement shall deal with 
something specific and fairly homogeneous, 
and the record pertains only to the factor 
under control. Our gardener’s measure of 
the quality of tomatoes may or may not 
represent a quality of his potatoes, peas or 
roses. Hach article must be measured by 
itself. So, only when we have collected a 
sufficient number of data to feel that all 
the essential and fundamental traits of in- 
telligence are represented, can we speak of 
an adequate measure of intelligence. The 
same principle applies to the measure of 
musical ability. 
Turning to the third question, as to the 
significance of a measure of a singer, we 
note that, if it is adequate, it places at the 
disposal of those who can profit by it a 
classified invoice of useful facts about this 
singer in such a way that it may be of 
direct value. The advice based upon such 
an invoice should be weighed by the ex- 
pert, the facts should be laid before the 
teacher, and the pupil should realize that 
she has become objectified to herself in 
