Note 2 — Chapter I · THE MULL OF CANTYRE.

Mr. Darwin evidently alludes to this circumstance in his Notes on St. Helena. He says, “I was standing on the edge of a plain, terminated by a great cliff of about a thousand feet in depth, when, at the distance of a few yards to windward, I saw some tern struggling against a very strong breeze, whilst where I stood the air was quite calm. Approaching close to the brink, where the current seemed to be deflected upwards from the face of the cliff, I stretched out my arm, and immediately felt the full force of the wind: an invisible barrier, two yards in width, separated perfectly calm air from a strong blast.”