Croll, James, 1821-1890 (physical geologist and Keeper of Maps and Correspondence, Geological Survey of Scotland)

Scope and Contents Letter to Sir Charles Lyell from James Croll concerning the temperature of space in relation to the position of the earth and the sun and discussing different methods of calculating the rate at which the temperature decreases and increases depending on the amount of heat that is received from the sun, 24 April 1866.

Scope and Contents Letter to Sir Charles Lyell from James Croll concerning the temperature of the earth in both winter and summer and how this temperature is affected by the position of the earth in relation to the sun and snow and ice throughout the world, 23 April 1866.