400 Thought Reading. [July, 
the grand distinctive feature of electricity, dividing it from 
heat and light, which aCt not, except through their proper 
media. Nerve current being a force bearing a wondrous 
resemblance to electricity, will there be no analogous phe- 
nomena of aCtion at a distance in nerve current ? 
What is the nature of nerve current ? We know not ; 
neither, according to Professor Tait, do we know the nature 
of electricity. 
A wishes to know the thought of B ; how does he place 
his own nerve current in relation with that of B ? 
The respective sensoria of A and B are not brought into 
juxtaposition, because externally the skull is not sensitive. 
Operators and subjects have sometimes been charged with 
laying their heads together : in such cases thought reading 
is of course metaphorical. 
There are reasons why the hand should be used as the 
instrument for receiving the influence of the nerve current. 
It is extremely sensitive ; but, above all, the brain is well 
accustomed to aCts of discrimination founded on nerve 
current coming from the hand. A, we may suppose, is 
blindfolded. Touch any other part of his body with a 
hazel nut, he is doubtful ; let it be brought into contact 
with his hand, he is sure. This is a sense of impression. 
True, but the brain is accustomed to judge what a thing is 
that sends up a message from the hand. The nerve current 
from the hand goes straight to the thalamus. No light is 
thrown upon the matter there. So the thalamus sends off 
the current, like a brush, to the grey cortex of the brain, 
where the current set up by the little hazel-nut is judged : 
not round enough for a marble ; not heavy enough for a 
bullet ; too hard for a little worsted ball ; and so forth, till 
the conclusion is reached : it is a hazel-nut : down comes a 
message to the striated body, to be delivered to the organs 
of voice — say aloud, “ It is a hazel-nut.” Such is the ordi- 
nary course of a sense impression from the hand. 
Let us now dispense altogether with the presence of the 
tangible objeft, and suppose that instead of being excited by 
the touch of a hazel-nut, the nerves in the hand of A are 
excited by the nerve current in the hand of B whilst he is 
thinking of a hazel-nut. A’s hand will send a nerve message 
to his brain. Of what kind ? Of no kind in particular ? 
Quite incredible. What should particularise it ? Its 
efficient cause, namely, B s nerve current, generated by a 
brain the physical condition of which corresponds with the 
thought of a hazel-nut. It seems to me highly probable 
that A would become more or less vividly conscious of an 
