12 
Proceedings of the Royal Society 
which still farther illustrated the mental action in certain optical 
phenomena. An article in the “Edinburgh Review” of October 
1858, describes thus the effect of the Pseudoscope: — “When an 
observer looks with it at the interior of a cup or basin, he not un- 
frequently sees it at first in the real form, but by prolonging his 
gaze, he will perceive the conversion within a few minutes ; and it 
is curious, that while this seems to take place quite suddenly with 
some individuals, as if the basin were flexible and were suddenly 
turned inside out, it occurs more gradually with others, the con- 
cavity slowly giving place to flatness, and the flatness gradually 
rising into convexity.”* 
Wheatstone was exceedingly interested in this discovery of the 
interference of mental action with optical phenomena, and invented 
several instruments with the view of ascertaining the principles on 
which it depended. The subject led him to study the subject of 
nervous organisation ; but it is believed, that he effected no special 
discoveries in that field. 
In 1834 the science of Electricity began to occupy Wheatstone’s 
attention. He endeavoured to ascertain the velocity of the elec- 
trical current. He invented many most ingenious machines with 
that view. He seems to have made only an approximation to the 
truth, viz., that the current travelled through a mile of wire in less 
than the 360th part of a minute. 
It now occurred to him that electricity might be employed in 
conveying intelligence along great distances by moving a magnet. 
By this time an idea of the same kind had occurred in G-ermany. 
Mr Cooke, when there, had become informed of the investigations 
by Schilling, and having come to London, made these known to 
Wheatstone. A proposal for a partnership between the two, was 
suggested, and was carried out. Messrs Cooke and Wheatstone 
A curious circumstance, analogous to the phenomena here described, 
was, without the help of any instrument, observed by me and other friends 
lately, in watching the revolutions of a cup anemometer on the top of Alnwick 
Castle. On looking at the instrument, it was seen revolving in a direction 
consisting with the truth ; but on continuing to look at it, in about half a 
minute the anemometer suddenly appeared to change the direction of its 
rotation, and to continue so to rotate. We remained for some time looking at 
the instrument to repeat the experiment. The same result on every occasion 
followed, and to every one of the party, eight or nine in number. 
