Theory of rain

James Hutton's two-part paper putting forward a theory about rain based on the Law of Nature.

Date: Written in 1784.
Publication: Transactions of the Royal Society of Edinburgh, Volume 1, 1788, Pages 41-86.

This paper highlights the diversity of James Hutton's scientific interest and work.

Although later renowned for his work on the theory of the earth, he was also interested in meteorology, and studied the changes in the earth's atmosphere.

In his paper, Hutton explains why rain forms, using rainfall data and observations on the climate from around the world. He concluded that rainfall was regulated by two factors:

- The humidity of the air
- The mixing of different air currents in the higher atmosphere.

Part 1 of the paper is entitled 'Investigation of the Law of Nature, on which is to be founded a Theory of Rain'. Hutton read this to the Royal Society of Edinburgh on 2 February 1784. It appears in the transactions on pages 41-51, with a diagram on page 43 showing rates of water evaporation. Hutton refers to Joseph Black's theory of latent heat on page 49.

Part 2 is headed 'The Theory of Rain applied to natural appearances'. Hutton read it to the Royal Society of Edinburgh on 12 April 1784. In the Society'sTransactions, it appears on pages 52-86.