Nikola Tesla and the Pigeon

This Tesla item is from the Perimeter Institute, in Canada -- "What Great Scientists Did When they Weren't Doing Great Science." They have several more here.

One they didn't mention, but that I particularly like, was Arthur Eddington's method of tracking lifetime cycling progress -- the largest integer N such that one had cycled at least N miles on N different days.

He got up to at least N=77, which he reached at the age of 60.

Some people call this the "Eddington Number," which is funny because Eddington is known for (among many other things) his interest in the fine structure constant α, which he claimed was exactly equal to 1/136, and for his calculation that the exact number of protons in the universe (with an equal number of electrons) was N_EDD = 136 × 2²⁵⁶ ∼ 10⁷⁹, or, as he said in a 1938 lecture at Cambridge:

"I believe there are 15 747 724 136 275 002 577 605 653 961 181 555 468 044 717 914 527 116 709 366 231 425 076 185 631 031 296 protons in the universe and the same number of electrons."

Later, when α was experimentally found to be closer to 1/137, Eddington changed his "proof" to claim that α had to be exactly 1/137, for which Punch magazine dubbed him "Sir Arthur Adding-One."