In the book Eyewitness DK Electricity, there's a photo of a page from Michael Faraday's notebook dated August 29, 1831, showing a sketch of his "induction ring apparatus," and a photo of what appears to be the very first transformer, which was a toroid. In fact, this photo graces the frontispiece of the book.
In the drawling, the A winding occupies the left half and the B winding the right half. Faraday wrapped two layers of windings around a 6" soft iron ring, with the windings insulated with calico cloth. He dragged the A wire over a battery and noticed a spike of induced current in the B wire.
Sadly, as Faraday lacked AC, he was unable to much more with the first transformer.
I hereby propose August 29 as National Toroid Day, and suggest that FPQRP obtain a special-event callsign for that day.