s own powers at odd and end times with ease and nicety,
if he happens to have ready access to suitable apparatus.

The use of tests, which, objectively speaking, run in a geometric
series, and subjectively in an arithmetic one, may be applied to
touch, by the use of wire-work of various degrees of fineness; to
taste, by stock bottles of solutions of salt, etc., of various
strengths; to smell, by bottles of attar of rose, etc., in various
degrees of dilution.

The tests show the sensitivity at the time they are made, and give
an approximate measure of the discrimination with which the operatee
habitually employs his senses. It does not measure his capacity for
discrimination, because the discriminative faculty admits of much
education, and the test results always show increased delicacy after
a little practice. However, the requirements of everyday life
educate all our faculties in some degree, and I have not found the
performances with test weights to improve much after a little
familiarity with their use. The weights have, as it were, to be
played with at first, then they must be tried carefully on three or
four separate occasions.

I did not at first find it at all an easy matter to make test
weights so alike as to differ in no other appreciable respect than
in their specific gravity, and if they differ and become known apart,
the knowledge so acquired will vitiate future judgments in various
indirect ways. Similarity in outward shape and touch was ensured by
the use of mechanically-made cartridge cases; dissimilarity through
any external stain was rendered of no hindrance to the experiment by
making the operatee handle them in a bag or with his eyes shut. Two
bodies may, however, be alike in weight and outward appearance and
yet behave differently when otherwise mechanically tested, and,
consequently, when they are handled. For example, take two eggs, one
raw and the other hard boiled, and spin them on the table; press the
finger for a moment upon either of them whilst it is still spinning:
if it be the hard-boiled egg it will stop as dead as a stone: if it
be the raw egg, after a little apparent hesitation, it will begin
again to rotate. The motion of its shell had alone been stopped; the
internal part was still rotating and this compelled the shell to
follow it. Owing to this cause, when we handle the two eggs, the one
feels "quick" and the other does not. Similarly with the cartridges,
when one is rather more