Can you describe Sai Baba's unusual sleeping plank mentioned in Chapter 10 and explain how it was possible for him to use it?

Certainly. Chapter 10 details Sai Baba's unique sleeping arrangement on a wooden plank that was just four cubits long and a mere one span (approximately 9 inches) wide. This narrow plank was suspended from the rafters by old rags, like a swing. Baba would sleep on this precarious perch, often with lamps burning at his head and feet. The chapter addresses the physical impossibility of this by attributing it to his great Siddhis, or divine powers. It suggests the plank was "merely for name’s sake" and that his ability to get on and off it without anyone ever seeing him was a manifestation of these powers, likening his imperceptible movements to those of flies or ants.