Have a look at this article on a famed example of the 247.
The image at the top is the aircraft during its flights with the RAF, likely some time in 1944. Note the reverse-slope windows that are a hallmark of the 247.
Now look at the other aircraft in the same article. They have conventional style slope-down windows. Those two images are from before 1944, one in the 30s and the second around 41/42.
Does anyone know what's going on here? Were certain batches one way or the other?
From the Boeing 247 article (emphasis mine):
The cockpit windshield of the first 247s was angled forward, instead of the conventional aft sweep. This was the design solution (similar to that adopted by other contemporary aircraft that used a forward-raked windscreen) to the problem of lighted control panel instruments reflecting off the windshield at night, but it turned out that the forward-sloping windshield would reflect ground lights instead, especially during landings and it also increased drag slightly.[13][14] By the introduction of the 247D, the windshield was sloped aft in the usual way, and the night-glare problem was resolved by installing an extension (the glarescreen) over the control panel.[15]
