NavList:

Brad you wrote: David  I suggest you fill your screen with the artificial horizon in the image of Amundsen at the pole. It looks like there are adjustable (nuts and threaded rod?) legs in the front right and rear right corners.  To my eyes, we also see the top of one in the back left.  That would be consistent with a mirror!

I spotted the lighter bits at two corners too, despite what it says in the text.  That’s why I said I was prepared to be persuaded.  I tried to find some primary evidence by quickly looking in ‘The South Pole’, but without reading the whole book again, I couldn’t find any.  The same picture in Roland Huntford’s book, ‘The Amundsen Photographs’ which appears to be where the phrase “which is a tray of mercury” comes from, is too fuzzy to tell.  Clearer images on the www do appear to show something at the corners.  DaveP