11 January—It must be almost 40 years ago that, as the sun came out after a typical morning rain in Devon, southwest England, the kids and I saw a rainbow over a meadow. There was a gravel road through the meadow, so I was actually able to drive the hired Rover to the end of the rainbow. Not being a rainbow chaser, I didn’t expect to find a pot of gold, to be sure. But hope sprang.

So I was only a little disappointed—but, given my luck, not at all surprised—that at the end of the Devon rainbow was an outhouse, a one-hole privy. Too bad I hadn’t taken the camera along on that drive.

Technically, since rainbows are full circles, they don’t have ends. We see them as arcs only because of our perspective on the ground. And as the Rover neared the one-holer the rainbow dissolved.

That said, here are four rainbows for your entertainment, edification, and admiration. The top one was home-grown in Litchfield. The one under that was photographed in Oxford, England. As for the two full arches at the bottom, I have no idea. But they’re magnificent, especially the double one between the tors. Let’s assume they weren’t created by digital means.

In addition to their shape, all rainbows always, guaranteed, and without fail, exhibit the same colors—red, orange, yellow, green, blue, indigo, violet—in the same order, all of it dictated by good, reliable, old-fashioned physics, because of how light separates into different wavelengths as it passes through water droplets. So let’s hear it for the mnemonic physicist Roy G. Biv . . .