Note 18 — PART II. BRITISH FOREST TREES USED AS NAVAL TIMBER.

There is yet no sufficient data for the term alpine plant, but with reference to latitude. The influence on vegetables, arising from rarefaction and diminution of pressure of atmosphere, from difference of stimulus of solar ray—when the entire ray of light, heat, and chemical power, though less intense, is radiated fresh, and not much broken or modified by refraction and reflection, and heat communicated more in proportion by radiation than by contact of heated air; or from difference of electric or galvanic or other meteoric impression connected with altitude or ranges of mountains, or with primary rocks or more upright strata, has not been made the subject of research, at least has not been sufficiently investigated by any naturalist.