A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2016 May 30, 14:49 -0700
Stan, you wrote:
"I note that there is a typo in either Hart's original or your transcription. It shows the sum correctly as 19.37899. Half of this is 9.689495, so, to five decimal places, the half-sum should be either 9.68949 or 9.68950, but not 9.68849. The time shown of 3-54-16 is correct for 9.68949 (or so)."
Thanks! I was curious enough to check, and it turns out the typo was in the original (I would have guessed it arose in auto-transcription, but that is so good these days...). I've attached below a screen capture from the original page with the section I quoted previously. I wonder if Hart got letters from attentive readers back then?!
Also I'm including a screen cap of another reference to a time sight in the same book which I discovered just now by searching on "secant" as a quick way to get to the page with the calculation. This one Hart intended for comedy. For us today it's yet another example of my claim that navigation was acceptable as "women's work" back then.