Davidson asks for his views on his theories on relationships between heat, electricity and magnetism. He encloses copies of letters he has previously sent to Humphrey Davy and Barlow to Davidson, 11 February 1831, where he solicits their views. The Davy letter is the most detailed and sets out his views on the connection between electricity and heat or caloric: "What if they are the same in different states or modes of action. The caloric emitted in combustion and dissolution of bodies may be compared to the separation of spirit from a gross earthly body".
Dated at: Glasgow.