Whilst doing a little research on our friend, Isaac Newton, I cam across this lovely piece of trivia. Long story short: on Wikipedia, you can go from “Pet Door” to “Isaac Newton” in one click.
In an apparent early modern example of urban legend, the invention of the pet door was attributed to Isaac Newton (1642–1727) in a story (authored anonymously and published in a column of anecdotes in 1893) to the effect that Newton foolishly made a large hole for his adult cat and a small one for her kittens, not realizing the kittens would follow the mother through the large one. Two Newton biographers cite passages saying that Newton kept “neither cat nor dog in his chamber”. Yet over 60 years earlier, a member of Newton’s social circles at Trinity, one J. M. F. Wright, reported this same story (from an unknown source) in his 1827 memoir, adding: “Whether this account be true or false, indisputably true is it that there are in the door to this day two plugged holes of the proper dimensions for the respective egresses of cat and kitten.”
Text via Wikipedia.