“Going nineteen to the dozen” means going at breakneck speed.
Apparently, it arose during the heyday of the Cornish tin and copper mines, which were often hit by floods. In the 1700s, coal-powered, steam-driven pumps were installed to clear the water. When working at the top rates, the pumps could clear nineteen thousand gallons of water for every twelve bushels of coal burned.
A modern example of its use comes from the Daily Mail of October 23, 2003: “Talking nineteen to the dozen, her conversation is still peppered with outrageous references and bawdy asides.” The picture we get is that the rate of talking is so great that when other people say merely a dozen words, the speaker gets in nineteen.
It’s also sometimes used to describe a rapid heartbeat in times of danger, and to refer to other fast-moving or fast-changing things.
There’s a version in Australia, also known in Britain, that reads “ten to the dozen.” A recent example is this one from the Liverpool Echo: “He’s witty and irreverent and talking ten to the dozen about his upcoming projects.” Logic would assume that something going at that rate to be slower than usual. However, all the examples in print show it is meant in the same sense as “nineteen to the dozen,” that something is going very fast.
It would be nice if the use of English was always logical. On the other hand, that might be rather boring, and I’d have to write nineteen to the dozen to liven things up around here.