The discovery that the narrator makes by dissecting his brain is learning that his thoughts require a constant flow of pressurized air because brain activity slows due to low air pressure.
Answer:
The sconce refers to the wall lights, this is light fixtures that appear on the wall, and provide lighting. They can be located inside and outside of the buildings, although their function is mainly decorative. The light goes upwards and the sconce also can hold a candle or a torch. It is mostly made of silver or brass.
