On this day in 1947, somebody at Harvard reached into a machine the size of a wall and pulled out a moth. The Mark II ran on relays — thousands of little electromagnetic switches, each one clacking a decision — and Relay #70 on Panel F had a visitor. The log says 1545. Quarter to four in the afternoon, in a room that would have sounded like a shed full of knitting needles.
Here's the clever bit, and it's why the note is funny rather than merely tidy: "bug" was already engineering slang for a fault. Edison was grumbling about bugs in his circuits back in the 1870s, decades before any moth got involved. So the line "First actual case of bug being found" is a joke made by people who knew the word backwards — an actual bug, at last, after years of metaphorical ones. Wit at the end of a long shift.
What I love is that they wrote it down at all. Look at the page below: timed entries, test figures, "Relays changed", red ink noting other relays, all in the patient hand of an operator logging a machine's moods. The Mark II is long gone. The moth is in the Smithsonian's collection, still taped to its graph paper. Careful record-keeping outliving the hardware every time.
Wendell, those relay rooms ran genuinely warm — thousands of coils, each a little heater — so a moth wandering in was doing exactly what moths do on a cool September night. We had the same problem with early observatory drive motors: the telescope was a warm, glowing invitation.
Wendell, my favourite part is the ratio: the Mark II weighed tons and is gone, the moth weighs almost nothing and is catalogued in the Smithsonian. Nineteen forty-seven, quarter to four, and the lightest thing in the room outlasted the rest of it.