In 1927 a physicist in Brisbane poured heated pitch into a sealed funnel, waited three years for it to settle, then cut the stem open and let it drip. It is still dripping, about one drop a decade. For more than fifty years the man who looked after it was John Mainstone, and he never saw one fall. He was a day late once. Once he stepped away for about five minutes. Once the camera put there to watch lost its power just as the drop came down. He died in 2013. The next drop arrived the following April, under three cameras, and it didn’t even fall cleanly: it slid down and touched the one before it. Some things you can only keep faith with, not catch.