Note 42 — Chapter IV

I have often seen the white thin, morning cloud, edged with the seven colors of the prism. I am not aware of the cause of this phenomenon, for it takes place not when we stand with our backs to the sun, but in clouds near the sun itself, irregularly and over indefinite spaces, sometimes taking place in the body of the cloud. The colors are distinct and vivid, but have a kind of metallic lustre upon them.