248 THE HORSE OF MR. VON OSTEN 



he would pronounce emphatically the word "and". 

 After this had been done a number of times, he put up two 

 of the pins and obscured them by the cloth. The cloth 

 was again raised'^nd the word " and " pronounced. Then 

 Hans, as a result of his previous instruction (so Mr. von 

 Osten thought) would give two taps at sight of the pins. 

 The thing was repeated with three pins, then with one, 

 and so on, and the horse would always execute the proper 

 number of taps. 



Now, five pins were set up, the three to the right being 

 covered by the cloth. The horse tapped twice and Mr. 

 von Osten said " two ". Then the cloth was raised, Hans 

 gave three further taps, and Mr. von Osten said " and 

 three " with emphasis. 



In this simple manner he tried to get the horse to un- 

 derstand that the three belongs to the two, and that both 

 together make five. The image of the five pins as it was 

 known from previous experience, was to be associated 

 with the combined groups of two and three, and con- 

 versely, it was to be reproduced when these groups were 

 presented. Later the cloth and pins were omitted and the 

 question was asked: "How much is two and three?". 

 The horse tapped five times. It had learned how to add. 

 Still this could be regarded only as a mechanical process, 

 if the horse were able to add only those numbers which 

 had been presented together one or more times in the 

 manner just described. And so long as we remained 

 within the first decade, we could get twenty-five binary 

 combinations whose sum does not exceed lo (counting 

 inverted orders we would have forty-five binary permu- 

 tations), — all of which might have been practised sepa- 

 rately. But as a matter of fact, Mr. von Osten did not 

 take this course, for as he himself says, he allowed Hans 



