In France, a chemist named Pilatre de Rozier tested the flammability of hydrogen by gulping a mouthful and blowing across an open flame, proving at a stroke that hydrogen is indeed explosively combustible and that eyebrows are not necessarily a permanent feature of one's face.

The remarkable position in which we find ourselves is that we don't actually know what we actually know.

In the morning I awoke early and experienced that sinking sensation that overcomes you when you first open your eyes and realize that instead of a normal day ahead of you, with its scatterings of simple gratifications, you are going to have a day without even the tiniest of pleasures; you are going to drive across Ohio.

If you drive to, say, Shenandoah National Park, or the Great Smoky Mountains, you'll get some appreciation for the scale and beauty of the outdoors. When you walk into it, then you see it in a completely different way. You discover it in a much slower, more majestic sort of way.

I hadn't realized quite how extraordinary Charles Lindbergh's achievement was in flying the Atlantic alone. He had never flown over open water before, but he flew straight to Dingle Bay in Ireland and then on to Paris, exactly as planned.

If you go out on the Appalachian Trail, you have to bring so much more equipment - a tent, sleeping bag - but if you go hiking in England, or Europe, generally, towns and villages are near enough together at the end of the day you can always go to a nice little inn and have a hot bath and something to drink.

I mused for a few moments on the question of which was worse, to lead a life so boring that you are easily enchanted, or a life so full of stimulus that you are easily bored.