In Vol II, I believe there is a problem with the polarity of the ac power supplies in Figure 2.13. I am looking at the .pdf version, not sure about the others
The explanation is in the equation image preceding PDF figure 2.13 which is shown here
If you are concerned about the 8 V battery polarity being reversed, the DC battery cannot have a phase angle. However, it can have the polarity revesed to account for the 180 phase of the 8V angle 180 AC source. The 8V battery polarity is reversed to repersent the AC 8V angle 180 source.
The polarity of the 2V DC meter is reversed form the 2 V angle 180 meter for the same reason.