INTRODUCTION 



[By C. Stumpf] 



A HORSE that solves correctly problems in multiplica- 

 tion and division by means of tapping. Persons of unim- 

 peachable honor, who in the master's absence have re- 

 ceived responses, and assure us that in the process they 

 have not made even the slightest sign. Thousands of 

 spectators, horse-fanciers, trick-trainers of first rank, 

 and not one of them during the course of many months' 

 observations are able to discover any kind of regular 

 signal. 



That was the riddle. And its solution was found in 

 the unintentional minimal movements of the horse's ques- 

 tioner. 



Simple though it may seem, the history of the solu- 

 tion is nevertheless quite complex, and one of the im- 

 portant incidents in it is the appearance of the zoologist 

 and African traveler. Schillings, upon the scene, and 

 then there is the report of the so-called Hans-Commis- 

 sion of September 12, 1904. And finally there is the 

 scientific investigation, the results of which were pub- 

 lished in my report of December 9, 1904. 



After a cursory inspection during the month of 

 February, I again called upon Mr. von Osten in July, 

 and asked him to explain to Professor Schumann and 

 me just what method he had used in instructing the 

 horse. We hoped in this way to gain a clue to the 



