I shouldn’t be allowed to use the internet. An offhand comment can lead me into an obsessive bout of searching and the combined evils of Wikipedia and Google Books can lead to danger.
I bloody love Google Books.
When Peter Lemon of The Casks innocently wondered on Facebook why US Proof is double the alcohol by volume percentage rather than the old British measure of about 1.75 times, he probably didn’t realise what he’d done. The seed of research was planted, and here’s all I now know about proof.