ii8 THE HORSE OF MR. VON OSTEN 



moment I was to tap upon one of a series of keys ar- 

 ranged like those of a piano, with the middle finger of 

 my right hand — corresponding to the right forefoot of 

 the horse. The questioner observed my key, I, his head, 

 — just what had happened in the experiments with Hans. — 

 and as soon as I perceived the involuntary closing signal 

 I reacted upon it by releasing, suddenly, another key 

 upon the same keyboard, which I had in the meantime 

 been pressing down with my second finger, thus marking 

 what with Hans had been called the backstep. Each key 

 was connected with a separate electro-magnet, and these 

 in turn with markers, in such a manner that pressure 

 upon the keys closed two electric circuits and, releasing 

 the keys, opened them, and both the closing and the 

 opening were recorded upon the smoked paper by means 

 of the markers. And, finally, in order to ascertain the 

 time relations of all these processes, a time-marker in- 

 dicated the time in fifth-seconds upon the revolving 

 kymograph record. The time-curve was recorded just 

 below the other curves. 



Of the curves * thus obtained under the most equable 



* For registering the curves a Hering kymograph was used, with a 

 loop 2i metre* long. The kymograph rested on felt. With the aid 

 of the Marey model a pneumographic record was taken now of the 

 thoracic, now of the abdominal, breathing, never both simultaneously, 

 since this was extrinsic to my purpose, and it would have made the 

 whole experiment too complex. The time was recorded by means of 

 the Jacquet chronograph. For purposes of making more exact measure- 

 ments the acoustic current interrupter of Bernstein was used, attuned to 

 100 vibrations per second. But this necessitated such rapid revolution 

 of the drum of the kymograph that the curves were not compact enough 

 for purposes of demonstration. The levers were all fitted with micro- 

 meter adjustments. They wrote tangentially and, except the one reg- 

 istering the breathing curve, all points lay in one vertical line. The 

 error of deflection and that due to the rondure of the writing-surface, 



