However, it absolutely amazes me that they used square windows on a pressurised airframe. Even 50 years ago the science behind stress concentrations on corners was very well understood. Why did they do it???
Perhaps because there had been (and never were) any problems with the Douglas DC-6, DC-7, Lockheed 1049, Convairliners. I thought the cracks emanated from the astro window anyway, not the cabin windows (I could be wrong).