Pat Bellew has a daily blog with excellent math history: On This Day in Math. Today’s has a great gif of the Haberdasher’s Puzzle by Dudeney. Pat writes:
b. 4-10-1857 Henry Ernest Dudeney (pronounced with a long “u” and a strong accent on the ﬁrst syllable, as in “scrutiny”). He was England’s greatest maker of puzzles of mathematical interest, publishing six books of puzzles. His ﬁrst work appears under the pseudonym “sphinx.” Although he never met Sam Loyd, they were in frequent correspondence and informally exchanged ideas. … Some of Dudeney’s most famous innovations were his 1903 success at solving the Haberdasher’s Puzzle (Cut an equilateral triangle into four pieces that can be rearranged to make a square) and publishing the first known crossnumber puzzle, in 1926. In addition, he has been credited with inventing verbal arithmetic and discovering new applications of digital roots.
Pat points out that the Kindle edition of the Canterbury Puzzles is free!