NavList:

Robin Stuart posted:


That's great! I like the monkey. For anyone who hasn't followed the link, the painting is circa 1836.

Artwork can be an excellent source for period details that are otherwise lost. For example, common quadrants (usually called octants today) had no handles. So how do you hold one? The normal manipulation can be seen in numerous sketches, paintings, and in all those statuettes of a lieutenant taking a sight: you just grab the frame out below the horizon glass (with either hand! so this is before the lefty revolution that turned all sextants into left-handed instruments!).

And yes, calculations were frequently worked up on slates. It might be fair to say that this was the "normal" working medium. I have mentioned this many times in NavList messages but perhaps not recently. Often in calculations that are recorded in notes, even quickly and sloppily, you'll find typos --cases where there is an incorrect number but the math works out in the end. A likely explanation in these cases is that the work has been copied over, probably from a slate. Why do that? Maybe for study notes... maybe for later review... Or if the notes are careful and drawn out with some flourish, maybe for a "portfolio" to show off to a future employer.

Frank Reed