When you walk into a pub, one of the beers might be "on nitro." It's usually a dark beer (though lately, not always). It has been used to most famous effect by Guinness, which celebrates the "surge" it produces when a pint is poured into a glass. Indeed it was invented at Guinness by a mathematician named Michael Ash back in 1959. Today, the folks at the brewery in Dublin honored him. I'll have more about this moment in brewing history later, but here's a shot of the inventor enjoying the fruits of his labor.