The designs come from the book "Principles of decorative design" (published 1870); they were drawn by Christopher Dresser, the author of the book. ’Grotesque’ refers to a style of decorative art that uses odd and fantastic combinations of natural, human and animal forms, so that they are distorted and unnatural in shape or size into absurdity, ugliness or caricature. In medieval architecture, grotesques are carved stone sculptures commonly used as a decorative element. They are often confused with gargoyles, but the distinction is that gargoyles are figures or sculptures that contain a water spout through the mouth, while grotesques do not. To put it straight, gargoyles are both ornamental and functional as they convey water away from the sides of buildings.