Final answer:
The author's depiction of the pendulum builds suspense by emphasizing its slow, rhythmic, and mechanical motion, symbolically representing the inescapable passage of time and the character's dwindling chance of escape.
Step-by-step explanation:
The author's description of the pendulum in the passage indeed builds suspense, primarily through the use of vivid imagery and the symbolic representation of the inexorable passage of time. The slow, rhythmic description of the pendulum's movement creates a sense of inevitable doom, echoing the rhythmic tolling of a death knell. This technique effectively conveys a chilling mood and heightens the tension as the reader anticipates the fate of the character. The pendulum's relentless movement and the attention to its mechanical and rhythmic qualities suggest an impending sense of finality, evoking anxiety and suspense as the character's chances of escape diminish with each passing moment.