I next thought of another and much simpler test, but one which, by virtue of its very simplicity, could not be exposed to any elaborate and farfetched suspicions. I saw on one of the shelves in the stable a panel of cards, about the size of an octavo volume, each bearing an arabic numeral on one of its sides. I once more asked my good friend Krall, whose courtesy is inexhaustible, to leave me alone with his pupil. I then shuffled the cards and put three of them in a row on the spring-board in front of the horse, without looking at them myself. There was therefore, at that moment, not a human soul on earth who knew the figures spread at the feet of my companion, this creature so full of mystery that already I no longer dare call him an animal. Without hesitation and unasked, he rapped out correctly the number formed by the cards. The experiment succeeded, as often as I cared to try it, with Hanschen, Mohammed and Zarif alike. Mohammed did even more: as each figure was of a different colour, I asked him to tell me the colour--of which I myself was absolutely ignorant--of the first letter on the right. With the aid of the conventional alphabet, he replied that it was blue, which proved to be the case. Of course, I ought to have multiplied these experiments and made them more exhaustive and complicated by combining, with the aid of the cards and under the same conditions, exercises in multiplication, division and the extracting of roots. I had not the time; but, a few days after I left, the subject was resumed and completed by Dr. H. Hamel. I will sum up his report of the experiments: the doctor, alone in the stable with the home (Krall was away, travelling), puts down on the black-board the sign + and then places before and after this sign, without looking at either of them, a card marked with a figure which he does not know. He next asks Mohammed to add up the two numbers. Mohammed at first gives a few heedless taps with his hoof. He is called to order and requested to be serious and to attend. He then gives fifteen distinct taps. The doctor next replaces the sign + by X and, again without looking at them, places two cards on the blackboard and asks the horse not to add up the two figures this time, but to multiply them. Mohammed taps out, "27," which is right, for the black-board says, "9 X 3." The same success follows with other multiplication sums: 9 X 2, 8 X 6. Then the doctor takes from an envelope a problem of which he does not know the solution: fourth root of 7890481. Mohammed replies, "53." The doctor looks at the back of the paper: once more, the answer is perfectly correct. 16