How does Sarah Waters use imagery in Fingersmith?

Example of Imagery:

"The road was perfectly quiet and perfectly dark, and I imagined the sound of the horse, and the wheels, and our voices, carrying far across the fields. Then I heard, from rather near, the slow tolling of a bell - a very mournful sound, it seemed to me at that moment, not like the cheerful bells of London."

"It was odd to see her stepping out of that gloomy place, like a pearl coming out of an oyster."