get the same sum; but on counting her money, she found, to her surprise, that she had lost four cents. How did this happen?

ANSWER.-On the first view of the question, there does not appear to be any loss; for if it be supposed that in selling five apples for two cents she gave three of the latter sort (viz., those at three for a cent) and two of the former (viz., those at two for a cent), she would receive just the same money as she bought them for; but this will not hold throughout the whole, for, admitting that she sells them as above, it must be evident that the latter stock would be exhausted first, and consequently she must sell as many of the former as remained overplus at five for two cents, which she bought at the rate of two for a cent, or four for two cents, and would therefore lose. It will be readily found that when she had sold all the latter sort in the above manner, she would have sold only eighty of the former, for there are as many threes in one hundred and twenty as twos in eighty; then the remaining forty must be sold at five for two cents, which were bought at the rate of four for two cents, viz. :

THE BLIND ABBOT AND THE MONKS.

THE following capital puzzle, old as it is, will be found very amusing:A convent, in which there were nine cells, was occupied by a blind abbot and twenty-four monks, the abbot lodging in the centre cell, and the monks in the side cells, three in each, forming a row of nine persons on each side of the building, as in the accompanying figure.

The abbot, suspecting the fidelity of the monks, frequently went round at night and counted them, when, if he found nine in each row, he retired to rest quite satisfied. The monks, however, taking advantage of his blindness, conspired to deceive him, and arranged themselves in the cells as in fig. 2, so that four could go out, and still the abbot would find nine in each row.

The monks that went out returned with four visitors, and they were

arranged with the monks as in fig. 3, so as to count nine each way, and consequently the abbot was again deceived.

Emboldened by success, the monks next night brought in four more visitors, and succeeded in deceiving the abbot by arranging themselves as in fig. 4.

Again four more visitors were introduced, and arranged with the monks as in fig. 5.

Finally, even when the twelve clandestine visitors had departed, carrying off six of the monks with them, the abbot, still finding nine in each row, as in fig. 6, retired to rest with full persuasion that no one had either gone out or come in.

ANSWER.-How it came to pass that the abbot should become confused is easily explained. The numbers in the angular cells were counted twice; these cells belonging to two rows, the more therefore the angular cells are filled by emptying those in the middle of each row, the double counting increases the whole sum, and the contrary is the case in proportion as the middle cells are filled by emptying the angular ones.

This is a very ingenious puzzle, and the mental exercise it occasions will gratify every one, except