Template:Selected anniversaries/June 24
1709: The public test of the "Passarola", a primitive airship devised by priest and inventor Bartolomeu de Gusmão, fails to take place.
1880: Mathematician and academic Oswald Veblen born. His work will find application in atomic physics and the theory of relativity. Veblen will publish a paper (1912) on the Four color conjecture.
2008: Mathematician and academic Gerhard Ringel dies. Ringel was a pioneer of graph theory and contributed significantly to the proof of the Heawood conjecture (now the Ringel-Youngs theorem), a mathematical problem closely linked with the Four color theorem.
2016: Steganographic analysis of Boxes unexpectedly reveals previously unknown type of cryptographic numen. APTO engineers call it "a remarkable breakthrough."