Readers are now asked to find the quickest method of getting the party across the river.  How many passages are necessary from land to land?  By “land” is understood either shore or island.  Though the boat would not necessarily call at the island every time of crossing, the possibility of its doing so must be provided for.  For example, it would not do for a man to be alone in the boat (though it were understood that he intended merely to cross from one bank to the opposite one) if there happened to be a girl alone on the island other than the one to whom he was engaged.

377.—­STEALING THE CASTLE TREASURE.

The ingenious manner in which a box of treasure, consisting principally of jewels and precious stones, was stolen from Gloomhurst Castle has been handed down as a tradition in the De Gourney family.  The thieves consisted of a man, a youth, and a small boy, whose only mode of escape with the box of treasure was by means of a high window.  Outside the window was fixed a pulley, over which ran a rope with a basket at each end.  When one basket was on the ground the other was at the window.  The rope was so disposed that the persons in the basket could neither help themselves by means of it nor receive help from others.  In short, the only way the baskets could be used was by placing a heavier weight in one than in the other.

Now, the man weighed 195 lbs., the youth 105 lbs., the boy 90 lbs., and the box of treasure 75 lbs.  The weight in the descending basket could not exceed that in the other by more than 15 lbs. without causing a descent so rapid as to be most dangerous to a human being, though it would not injure the stolen property.  Only two persons, or one person and the treasure, could be placed in the same basket at one time.  How did they all manage to escape and take the box of treasure with them?

The puzzle is to find the shortest way of performing the feat, which in itself is not difficult.  Remember, a person cannot help himself by hanging on to the rope, the only way being to go down “with a bump,” with the weight in the other basket as a counterpoise.

PROBLEMS CONCERNING GAMES.

    “The little pleasure of the game.” 
                         MATTHEW PRIOR.

Every game lends itself to the propounding of a variety of puzzles.  They can be made, as we have seen, out of the chessboard and the peculiar moves of the chess pieces.  I will now give just a few examples of puzzles with playing cards and dominoes, and also go out of doors and consider one or two little posers in the cricket field, at the football match, and the horse race and motor-car race.

378.—­DOMINOES IN PROGRESSION.

[Illustration]

It will be seen that I have played six dominoes, in the illustration, in accordance with the ordinary rules of the game, 4 against 4, 1 against 1, and so on, and yet the sum of the spots on the successive dominoes, 4, 5, 6, 7, 8, 9, are in arithmetical progression; that is, the numbers taken in order have a common difference of 1.  In how many different ways may we play six dominoes, from an ordinary box of twenty-eight, so that the numbers on them may lie in arithmetical progression?  We must always play from left to right, and numbers in decreasing arithmetical progression (such as 9, 8, 7, 6, 5, 4) are not admissible.