Frank Podmore,
The Naturalisation of the Supernatural…
(1908)
“ It is not in fact difficult in such experiments to exclude the operation of sight. But it is a much more difficult matter to ensure that a hint of the number chosen shall not be given to the percipient by subconscious whispering or even, conceivably, by rhythmical movements of the agent's body. And the fact that when a curtain was interposed between the agent and percipient, or when they were placed in separate rooms, success became much more uncertain, and the percipient in some cases received no impression at all, seemed from this point of view extremely suspicious. ”
