During the middle of the nineteenth century forests were believed to have important influences on climate. As climate was more thoroughly understood it became evident that the major climatic controls were beyond the influence of forest cover, a finding which wholly discredited the earlier conclusions. It was evident to the forester and student of ecology, however, that a forest stand has important and under certain conditions critical influence upon plant succession. Accordingly, attention was given to local climate, or micro-climate. An understanding of the significance of the influence of the forest in micro-climate is dependent on comparative measurements which the paper of Mr. Jemison clearly sets forth.