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You're certainly on the right track, David C. Here's a "friendly" introduction to the computation of longitude in an odd little book authored just a few years later by one Joseph Hart. The book is called "The Romance of Yachting". It's a rambling and even charming dissertation on many topics, including navigation calculations. By following Hart's instructions here, you should be able to figure out more of what's going on in these calculations. 

Frank Reed

PS: When using AI, so that others can benefit from your discoveries, please indicate which AI you are chatting with. :) Is it Google chat (Gemini), Microsoft Copilot? Or is it one of the other stars, Claude AI, or ChatGPT? Or maybe another one?? As for me, I have spent much of the past hour getting Claude AI to transcribe hand-written logbook pages from the early nineteenth century. It's quite good at that task. I can read them myself usually, but it helps tremendously when the AI does its transcription since its output is typed and ready to save. :)

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