t, which in the
following exposition we shall designate as "the back step", was never
included in the count.) Now after Hans had ceased tapping, the
questioner would raise his head and trunk to their normal position. This
second, far coarser movement was not the signal for the back-step, but
always followed it. But whenever this second movement was omitted, Hans,
who had already brought back his foot to the original position and had
thereby put it out of commission, as it were, would give one more tap
with his left foot.

If it was true that these movements of the questioner guided the horse
in his tapping, then the following must be shown: First, that the same
movements were observed in Mr. von Osten in every case of successful
response; secondly, that they recurred in the same order or with only
slight individual changes in the case of all who were able to obtain
successful responses from the horse, and that they were absent or
occurred at the wrong time in all cases of unsuccessful response.
Furthermore, it was observed that it was possible to bring about
unsuccessful reactions on the part of the horse as soon as the movements
were voluntarily suppressed, and conversely, that by voluntarily giving
the necessary signs the horse might be made to respond at pleasure; so
that anyone who possessed the knowledge of the proper signs could
thereby gain control over the process of response on the part of the
horse. These requirements have all been fulfilled, as we shall see in
the following pages.

With regard to the regular recurrence of the movements noticed in the
case of Mr. von Osten, I was, after some practice, able to note
carefully their peculiar characteristics. This was rather difficult, not
only on account of their extreme minuteness, but also because that very
vivacious gentleman made sundry accompanying movements and was
constantly moving back and forth. To abstract from these the essential
and really effective movements was truly difficult. It was much easier
to observe these movements in the case of Mr. Schillings, probably on
account of the fewer accompanying movements and perhaps on account of
their greater distinctness. Usually he would raise the entire trunk a
trifle, so that the movements could be noticed from behind. Besides
these, I had an opportunity to observe the Count zu Castell, Mr. Hahn
and the Count Matuschka. All three made the same movements, though
somewhat more minutely than Mr. Schillings,