pitch drop

From this site:

In 1927 Professor Parnell heated a sample of pitch and poured it into a glass funnel with a sealed stem. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. From that date on the pitch has slowly dripped out of the funnel - so slowly that now, 83 years later, the ninth drop is only just forming.

Pitch appears solid at room temperature, the site says, or even brittle. It'll shatter if you hit it with a hammer. But it's actually flowing down...very, very slowly. What it doesn't say on the site is why Parnell decided on pitch for his experiment, which I'd be interested to know. There's a video which shows a year's worth of (non)movement:

And there's a live webcam at the site. The only thing you'll see moving is the clock and the people staring at the pitch to try to see it move. It's sort of fascinating - not watching it, that's pretty boring, but the concept and the fact that it's been going on for so long, and that no one's ever seen it drip. Apparently when it goes, it happens quite quickly, in about a tenth of a second...every ten to twelve years.

I showed this to Sherlock. He was initially interested in the solid-that's-actually-a-visco-elastic-polymer concept and watched the webcam for a few minutes.

Sherlock: What happens when the next drop falls?

Me: What do you mean what happens? It...falls.

Sherlock: But what happens? Does it explode?

Me: No...

Sherlock: Then why is everyone so excited about it? It's already happened eight times.

He may have a point there. I'll probably still check the site every now and then for video of the ninth drop though.