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[Greg Daspit]

A curve can reflect light to more places than a flat surface can.
In the picture where the nav/ lav window is reflecting, the cabin window next to it has a reflection closer to the mid point of the curve and in that picture the nav window appears flat to me. In pictures where it is not reflecting, the light reflection on the curve of the cabin window appears higher.
 Could it be that the angle for the flat glass is not at the correct angle to see a reflection in some pictures?
I thought one of the theories was that the window might be flat to limit distortion for navigation.

[Greg Daspit]

Larry Inman provided a higher resolution copy of the photo.  The lack of reflection and the presence of the shadow (red arrow) really look to me like there is no reflective material there.

Could it be that the coaming has been removed in that picture? The black line could be a groove for the flat glass and the glass is reflecting the exposed edge made to transition from a curve of the fuselage to the flat glass.

[Jerry Germann]

Could it be that the coaming has been removed in that picture? The black line could be a groove for the flat glass and the glass is reflecting the exposed edge made to transition from a curve of the fuselage to the flat glass.

It appears to me that inner coaming edges are in the photo.....if the window coaming was removed, one would think that he/she would see no indications of metal forming, rather a flat surface ( slightly curved to match the fuselage)  as one sees when viewing the standard window.

[Matt Revington]

From the Ameliapedia
"The Lockheed Electra 10E was fitted with low distortion windows in several positions to minimize refraction errors during celestial observations. [16] (Military navigators were later cautioned to avoid using windows for celestial observations, and not to observe celestial bodies below 11 degrees, due to the excessive refraction error.)[17] [10]"

http://tighar.org/wiki/Air_Navigation:_State_of_the_Art_in_1937
The citation is [16]Wright, Monte Duane, Most Probable Position, The University Press of Kansas, Lawrence/ Manhattan/ Wichita, 1972, p. 156

Since this window was probably  installed at the request of Manning, it seems likely he would have asked for a flat window  to minimize distortion/refraction.  Would there have been a viable case for him to want a window that opened to get totally distortion free measurements or would the wind/air speed made that impractical.

[Ric Gillespie]

From the Ameliapedia
"The Lockheed Electra 10E was fitted with low distortion windows in several positions to minimize refraction errors during celestial observations. [16] (Military navigators were later cautioned to avoid using windows for celestial observations, and not to observe celestial bodies below 11 degrees, due to the excessive refraction error.)[17] [10]"

http://tighar.org/wiki/Air_Navigation:_State_of_the_Art_in_1937
The citation is [16]Wright, Monte Duane, Most Probable Position, The University Press of Kansas, Lawrence/ Manhattan/ Wichita, 1972, p. 156

I just ordered a copy of the book.  We need to see if the author cited source.

Since this window was probably  installed at the request of Manning, it seems likely he would have asked for a flat window  to minimize distortion/refraction.  Would there have been a viable case for him to want a window that opened to get totally distortion free measurements or would the wind/air speed made that impractical.

The Pan Am Clippers used a hatch that could be opened, so yes, I think an openable hatch was possible.

[Ric Gillespie]

From the Ameliapedia
"The Lockheed Electra 10E was fitted with low distortion windows in several positions to minimize refraction errors during celestial observations. [16] (Military navigators were later cautioned to avoid using windows for celestial observations, and not to observe celestial bodies below 11 degrees, due to the excessive refraction error.)[17] [10]"

http://tighar.org/wiki/Air_Navigation:_State_of_the_Art_in_1937
The citation is [16]Wright, Monte Duane, Most Probable Position, The University Press of Kansas, Lawrence/ Manhattan/ Wichita, 1972, p. 156

Since this window was probably  installed at the request of Manning, it seems likely he would have asked for a flat window  to minimize distortion/refraction.  Would there have been a viable case for him to want a window that opened to get totally distortion free measurements or would the wind/air speed made that impractical.

My copy of Most Probable Position (1972) arrived today.  It's an interesting and useful book but the author doesn't cite a source for his statement about Earhart's windows. The actual quote is:
"If the navigator was not to open a hatch for celestial observations, and in the absence of a periscopic sextant, the designers had to provide windows or domes for the navigator's use. Aeronautical designers resist protuberances of all kinds. Amelia Earhart and Howard Hughes outfitted their world-flight airplanes lavishly. For celestial navigation, both provided low-distortion glass in various windows."

His comments about Earhart elsewhere in the book are largely inaccurate and the only source he cites is Last Flight.  He's not a reliable source, at least about Amelia Earhart.

[Jerry Germann]

Scrolling through the Purdue archives once again, I came across this image; http://earchives.lib.purdue.edu/cdm/singleitem/collection/earhart/id/285/rec/2
To me,it looks similar to how the lavatory window appears, while in the repair shop, an area of interest looking somewhat arch shaped. I believe the object responsible for the shading on the door,may be the coaming, that similar to the coaming found on the lavatory unit.

[Ric Gillespie]

This hi-res detail of the windows in a Luke Field wreck photo courtesy of Larry Inman shows some interesting, but unidentified, interior features.