

Radiation a Property of Heat. Prismatic Spectrum. Invisible Rays. Two Hypotheses. Invisi- 

 ble Rays alike in their Properties to luminous Rays. Discoveries of Leslie. Differential Ther- 

 aoineter. Radiation, Reflection, and Absorption. Effect of Screens. Supposed Rays of Cold. 

 Common Phenomenon explained. Theory of Dew. 



