During 1799, Beddoes and Davy published "Contributions to physical and medical knowledge, principally from the west of England" and "Essays on heat, light, and the combinations of light, with a new theory of respiration. On the generation of oxygen gas, and the causes of the colors of organic beings." Their experimental work was poor, and the publications were harshly criticized. In after years Davy regretted he had ever published these immature hypotheses, which he subsequently designated "the dreams of misemployed genius which the light of experiment and observation has never conducted to truth."