I bought a thermometer at the beginning of the summer and was surprised how much I used it when the fish weren't biting. It explained a great deal and was worth the investment. I fished for ten years without one but then again I fished for a number of years without finally getting polarized sunglasses too.
Good article. I have a fishing log but unfortunately rarely write in it. I wish I did. It's kind of neat to look back at old entries and see what I was using and where. The dates and water conditions are also worth remembering.
"I often do not start fishing until the cool of the evening..."
Norman Maclean: A River Runs Through It