I don’t play bridge, so I’m posting this somewhat blindly. It was devised by W.H. Whitfeld, card editor of the Field, apparently in the late 19th century. The reader who submitted it to the Strand wrote, “If you don’t know the solution, I guarantee that it will take you or any of your staff three or four days.”

“We have a higher opinion of our readers’ skill than to allot them such a time-limit as this,” wrote the editors. “But certainly anyone who can solve this problem in three or four hours will have good cause to be congratulated on his ingenuity.”

When the Chevalier de Rohan was sent to the Bastille in 1674 on suspicion of treason, he knew there was no evidence against him except what might be extracted from one other prisoner. His friends had promised to communicate the result of that examination, and in sending him some fresh clothing they wrote on one of the shirts MG DULHXCCLGU GHJ YXUJ, LM CT ULGC ALJ.

For 24 hours de Rohan puzzled over the message, but he could make no sense of it. Despairing, he admitted his guilt and was executed. What was the message?

From Henry Dudeney:

The ilustration represents a square tablecloth of choice silk patchwork. This was put together by the members of a family as a little birthday present for one of its number. One of the contributors supplied a portion in the form of a perfectly symmetrical star, and this has been worked in exactly as it was received. But the triangular pieces so confuse the eye that it is quite a puzzle to find the hidden star.

Can you discover it, so that, if you wished, by merely picking out the stitches, you could extract it from the other portions of the patchwork?

Amy and Betty are playing a game. They have a chocolate bar that’s 8 squares long and 6 squares wide. Amy begins by breaking the bar in two along any division. Betty can then pick up any piece and break it in two, and so on. The first player who cannot move will be clapped in chains and rocketed off to a lifetime of soul-destroying toil in the cobalt mines of Yongar Zeta. (I know, it’s a pretty brutal game.) Who will win?

A logic puzzle from Mathematical Circles (Russian Experience), a collection of problems for Soviet high school math students:

During a trial in Wonderland the March Hare claimed that the cookies were stolen by the Mad Hatter. Then the Mad Hatter and the Dormouse gave testimonies which, for some reason, were not recorded. Later on in the trial it was found out that the cookies were stolen by only one of these three defendants, and, moreover, only the guilty one gave true testimony. Who stole the cookies?

A devilish puzzle by Lee Sallows:

In the diagram above, nine numbered counters occupy the cells of a 3×3 checkerboard so as to form a magic square. Any 3 counters lying in a straight line add up to 15. There are 8 of these collinear triads.

Reposition the counters (again, one to each cell) to yield 8 new collinear triads, but now showing a common sum of 16 rather than 15.

This problem dates from at least 1774; this version appeared in the American Mathematical Monthly of December 1902:

Three Dutchmen and their wives went to market to buy hogs. The names of the men were Hans, Klaus, and Hendricks, and of the women, Gertrude, Anna, and Katrine; but it was not known which was the wife of each man. They each bought as many hogs as each man or woman paid shillings for each hog, and each man spent three guineas more than his wife. Hendricks bought 23 hogs more than Gertrude, and Klaus bought 11 more than Katrine. What was the name of each man’s wife?

(There are 21 shillings in a guinea.)

By T.R. Dowson. White to mate in 21 moves:

It’s not as hard as it sounds, though it’s a bit like a square dance in a submarine.

In a certain library, no two books contain the same number of words, and the total number of books is greater than number of words in the largest book.

How many words does one of the books contain, and what is it about?