Beware the Square

 Have you ever wondered why windows on airplanes are round when most other windows are square or rectangular? Before airlines had larger and faster jets the windows were square but after examining the wreckage of two planes in the early 1950s it was discovered that the the squared off corners of the windows collected 70% of the stress of the pressurized cabin causing them to fracture. Circular windows disperse the stress more evenly, plus there are now 3 panes per window leaving a margin for failure.