It seems that the orientation of the sphere was upside-down compared to current convention. The dark "earth" was the top part of the sphere and the light "sky" the bottom. Back in those days, the sphere apparently contained the actual rotating gyroscope, so for instance the last illustration in the picture, 30 degree climb, is how it indeed would show up when the sphere is held in constant orientation by the gyroscope and the aircraft is in 30 degrees climb.
At some point this was mechanism and convention apparently changed, because nowadays there is just a partial sphere surface that obviously does not contain the gyro, and the coupling to the gyro is such that it works the other way in the vertical direction. I guess this indeed more natural, with the "sky" being in the upper part of the partial sphere surface. Am I right?