I may be wrong here - I hope Charles Platt will set me straight - but I think the relay used in Exercise 15 is slightly different than the one we used back in Chapter 2 Exercise 7.

The drawing for Exercise 7 shows the arm of the relay, when the coil isn't powered, pointing in the direction of the coil. When the coil is powered, the magnetic field it creates pushes the arm away (upward). This caused the 2nd LED to light up in Figure 2-60.

But in Exercise 15 the relay shown there has the arm in the "up" position, away from the coil. When the coil is powered, it pulls the arm towards it.

When I was building my circuit, I was using a relay where the arm was pointing towards the coil when not powered... I had to visually inspect the opened one (Exercise 7) to see this... once I saw that, I was able to properly wire my circuit. If I had to modify the circuit in Figure 3-93, I'd have to show the anode of the diode connected to the right-most pins (the one the arm is shown pointing at in Fig 3-93). I hope this makes sense... if we're to assume we're using the same relay from Exercise 7 here, then the circuit in Figure 3-93 would also need to have the arm pointing towards the coil.