Henry Ernest Dudeney/Modern Puzzles/140 - The Four-Colour Map Theorem/Historical Note

Historical Note on Henry Ernest Dudeney's Modern Puzzles No. $140$ - The Four-Colour Map Theorem

For just about $50$ years various mathematicians, including De Morgan, Cayley, Kempe, Heawood, Heffter, Wernicke, Birkhoff, Franklin and many others have attempted to prove the truth of this theorem,

and in a long and learned article in the American Mathematical Monthly for July-August, $1923$, Professor Brahana, of the University of Illinois, states that "the problem is still unsolved."

Martin Gardner, in his $1968$ repackaging 536 Puzzles & Curious Problems, refutes Dudeney's claim to have proved it.

He goes on to advertise his own contribution in his $1966$ Martin Gardner's New Mathematical Diversions from Scientific American.

Sources

• Jul. - Aug., 1923: H.R. Brahana: The Four-Color Problem (Amer. Math. Monthly Vol. 30, no. 5: pp. 234 – 243)  www.jstor.org/stable/2299087
• 1926: Henry Ernest Dudeney: Modern Puzzles ... (previous) ... (next): Geometrical Problems: Various Geometrical Puzzles: $140$. -- The Four-Colour Map Theorem
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Combinatorial & Topological Problems: Map Coloring Puzzles: $442$. The Four-Color Map Theorem
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Answers: $442$. The Four-Color Map Theorem