The philosopher John Stuart Mill believed "the amount of eccentricity in a society has generally been proportional to the amount of genius, mental vigour, and moral courage it contained".
Be that as it may, Jonas Hanway did his bit for all these virtues. He lived in London in the 18th century, and tried something which no man had ever done before: he habitually used an umbrella to protect himself against the rain, an idiosyncrasy that caused great hilarity in his native city at the time.
But there was a less frivolous side to Hanway's character which was to bear fruit more than half a century after he had died. He was a life-long campaigner against the abuse of child labour, and it is widely acknowledged that it was due primarily to his efforts in this regard that the use of little boys for cleaning chimneys was prohibited by law.
In the Dark Ages, smoke from the home fires burning escaped through a hole in the roof, but by the 13th century chimneys as we know them had become common, and they have been with us ever since.
They depend for their effectiveness on the heating of the air by the fire, so that it becomes buoyant and rises up the flue. This effect is augmented by the downward pressure of the cooler, heavier air filling the rest of the room, which forces the warm air up the chimney in much the same way as atmospheric pressure forces mercury up the evacuated glass tube of a mercury barometer.
Moreover, the taller a chimney, the stronger the created draft will be, because a taller chimney carries a deeper "head" of warm, light air.
Various factors, of course, may interfere with this effective mechanism. The most common is a neighbouring obstruction - like a higher chimney-stack, a building, or a line of trees - that causes turbulence in the vicinity; once a volume of cold air is forced into the chimney-top by the turbulence, it sinks rapidly downwards to the room below, bringing with it an unpleasant puff of smoke.
And problems may also arise from the continual accumulation of particles of soot throughout the length of the chimney flue itself, so that for reasons of efficiency and safety, a chimney must be regularly cleaned.
In pre-Victorian times it was very common for unscrupulous masters to send small boys bodily up the flue to scrape away the soot. It was this practice that Hanway's agitation helped to stop, and the Chimney Sweepers Act, which banned it, reached the statute books 156 years ago today, on August 7th, 1842.