38 galton.org
38
Inquiries into Human Faculty
were equal when compared together, then we can concisely express the
relative merits of the two classes to which they respectively belong, by
saying that 160.6 in the one is equal to 500 (the median) in the other.
I frequently make statistical records of form and feature, in the streets
or in company, without exciting attention, by means of a fine pricker and
a piece of paper. The pricker is a converted silver pencil-case, with the
usual sliding piece; it is a very small one, and is attached to my watch
chain. The pencil part has been taken out and replaced by a fine short
needle, the open mouth of the case is covered with a hemispherical cap
having a hole in the centre, and the adjustments are such that when the
slide is pushed forward as far as it can go, the needle projects no more
than one-tenth of an inch. If I then press it upon a piece of paper, held
against the ball of my thumb, the paper is indelibly perforated with a fine
hole, and the thumb is not wounded. The perforations will not be found to
run into one another unless they are very numerous, and if they happen to
do so now and then, it is of little consequence in a statistical inquiry. The
holes are easily counted at leisure, by holding the paper against the light,
and any scrap of paper will serve the purpose. It will be found that the
majority of inquiries take the form of “more,”
“equal to,” or “less,” so I
arrange the paper in a way to present three distinct compartments to the
pricker, and to permit of its being held in the correct position and used by
the sense of touch alone.
I do so by tearing the paper into the form of a cross— that is,
maimed in one of its arms—and hold it by the maimed part
between the thumb and finger, the head of the cross pointing
upward. The head of the cross receives the pricks referring to “more “; the
solitary arm that is not maimed, those meaning “the same”; the long foot
of the cross those meaning “less.” It is well to write the subject of the
measurement on the paper before beginning to use it, then more than one
set of records can be kept in the pocket at the same time, and be severally
added to as occasion serves, without fear of mistaking one for the other.
