I wrote:
. . . illusions (outside the mind) and internal delusions (internal
states of mine).
I meant "internal states of mind" not mine, and that is not the kind
of error the book is about.
Optical illusions are of two types:
1. Things which trick the mind into seeing something not there (or
hide something which is there), which some people may see and others
may not. The author does not list this example, but during WWII it
was discovered that colorblind people cannot be fooled by many kinds
of camouflage, such as green nets deployed in the jungle to cover
artillery. Colorblind people with excellent vision who applied to be
airborne observers were initially rejected, but later the army
actively sought them out.
2. Objective, optical phenomena which would show up with a camera,
such as mirages. The book discusses "superior mirages" -- something I
had not heard of. In the northern latitudes under certain weather
conditions, the atmosphere acts as a telescope, making distant
objects appear much closer than they really are, including object
below the horizon. Quote:
To get a sense of just how compelling such mirages can be, consider
the comparatively recent experience of the Canadian captain Robert
Bartlett. On July 17, 1939, while sailing between Greenland and
Iceland, Bartlett suddenly spotted the coast of the latter country,
looming so large that he could easily make out many familiar
landmarks. Like John Ross, Bartlett estimated the apparent distance
of the coast at twenty-five or thirty miles away. But he knew its
actual distance was more than ten times that, since his ship was
positioned roughly 350 miles from the Icelandic coast. That he could
see land at all is astonishing -- akin to seeing the Washington
Monument from Ohio. And yet, Bartlett wrote, "If I hadn't been sure
of my position and had been bound for Reykjavik, I would have
expected to arrive within a few hours. The contours of the land and
the snow-covered summit of the Snaefells Jokull [glacier] showed up
unbelievably near."
- Jed
