Between Rainbows

I was sitting in my car one of my older phrontesteries, at the low wall near Joyce's tower in Sandycove, watching the rain whip the windscreen. I had intended to do some writing but became interested in a ship out near Howth (headless in rainclouds). Like Howth, the ship was barely visible. Then I noticed the rainbow, a real zinger, strengthening quickly, possibly the most colourful I've seen. Then a fainter double appeared. The ship is just visible in between the two, what's known apparently as Alexander's Band after Alexander of Aphrodisias (200 AD) who first named it.