Historical Context in The Canterville Ghost
Wilde set "The Canterville Ghost'' in the English countryside in the late 19th century. To best highlight the conflicts present in his tale, Wilde has the story primarily take place in Canterville Chase, an old, large mansion described in Gothic terms. However, Wilde mixes the elements of horror with comedy, juxtaposing traditional English ghost stories with symbols of the modern United States.
Wilde reveals Sir Simon, the ghost, to be a true artist completely devoted to the aesthetics of his craft, which in this case is creating and spreading terror. The ghost has no reasons behind his art, and he seeks no objective over than perfecting the beauty of it. This approach to art and aesthetics was known as Decadence. Wilde shares these traits with his creation and was a leading member of the Decadent movement in the 19th century.
Wilde is likely adopting a more popular notion of the Fourth dimension by using it to suggest that the ghost moves in ways that are different from and incomprehensible to the living. This is what allows the ghost to vanish from view or to move through physical objects. By providing a "scientific" name for what the ghost does, Wilde uses the narrator to reveal popular understanding of science at the end of the 19th century.