seen not merely the coasts of islands and of continents, as in voyages round the world, but that I have visited the interior of two great continents which present the most striking contrasts to one another-the Alpine landscapes of tropical America, and the dreary steppelands of Northern Asia. Such enterprises, with the particular direction of my studies, were felt as a stimulus to general views; they almost necessarily aroused and kept alive a purpose to treat the knowledge at present possessed of the sidereal and terrestrial phenomena of Cosmos in their empirical connection, in a separate work. Through larger views, and the comprehension of created things in celestial space as well as on earth-yielding to the suggestion of perhaps too bold a plan--the hitherto imperfectly seized idea of a Physical Geography thus gradually came to assume the shape of a Physical Cosmography.

The form of such a work, if it make any pretensions to a literary character, becomes, from the superabundance of material which the ordering mind must overrule, a matter of very difficult determination. The descriptions of nature must not be left without animation, and yet does the stringing together of mere general results produce even as wearisome an impression, as the heaping up of too many minute details of observation. I do not

flatter myself with having fulfilled every varied requisite in the composition, with having always escaped the rocks which I am only competent to point out. A faint hope does, however, possess my mind, founded on the favourable reception by the public of the small work which I published soon after my return from Mexico, under the title of "Views of Nature." This work treats of several particular portions of the life of the earth—the physiognomy of plants, grassy plains and deserts-under general points of view. It has had more influence through what it has excited in susceptible youthful minds, possessed of fancy, than through aught that it has bestowed. In the Cosmos, upon which I am now engaged, as in the "Views of Nature," I have sought to show that a certain completeness of treatment of the particular subjects was not incompatible with a certain liveliness of colouring in the representation.

As public lectures afford an easy and decisive means of testing the excellence or indifference of arrangement in the particular parts of a doctrine, I made a point of delivering a Course of Lectures, of several months' duration, on the Physical History of the World, as I had conceived this science, first at Paris, in the French language, and subsequently at Berlin, within the walls of the University, and in the great Singing Academy simultaneously, in my native tongue. Speaking without notes, I have no

memoranda either of my French or German lectures. Even the notes that were made by some of my more diligent auditors have remained unknown to me, and have therefore not been used in the composition of the work which now appears. With the exception of the first forty pages of the first volume, the whole was written by myself, and for the first time, in the course of the years 1843 and 1844. Where present states of observation and opinion (and increasing abundance in the former brings about irrevocable changes in the latter) are to be portrayed, the representation gains, I imagine, in interest, in freshness, and in intimate life, when it is connected with a determinate epoch. The Lectures and Cosmos, consequently, have nothing more in common than the sequence in which the subjects they embrace are treated. I have only left the "Introduction" with the form of the Discourse, in which the subjects it comprises were in part at least originally presented.

It may perhaps be agreeable to the numerous audience which, with so much kindness, followed my course delivered within the walls of the University of Berlin, (between the 3rd of November, 1827, and the 26th of April, 1828, in 61 lectures,) if I here add a note of its divisions, as a memorial of times now long gone by. They were as follows: Nature and Boundary of the Physical Descrip

tion of the Universe, and General Survey of Nature, five Lectures; History of the Contemplation of the Universe, three Lectures; Motives inciting to the Study of Nature, two Lectures; Celestial Space, sixteen Lectures; Figure, Density, Internal Heat and Magnetism of the Earth, and the Northern Light, five Lectures; Nature of the Solid Crust of the Globe, Hot Springs, Volcanic Action, four Lectures; Rocks and Types of Rocky Formations, two Lectures; Figure of the Earth's Surface, Divisions of Continents, and Elevation of Mountains along Fissures, two Lectures; The Liquid Envelope-the Ocean, three, and the Gaseous Envelope-the Atmosphere, including the distribution of heat, ten Lectures; the Geographical Distribution of Organized Beings in general, one Lecture; the Geography of Plants, three; the Geography of Animals, three; and the Races of Man, two Lectures.

The first volume of my work comprises introductory considerations on the various sources of our enjoyment of nature, and the establishment of the laws of the universe; the circumscription and scientific treatment of Physical Cosmography; and a general picture of nature as a survey of the phenomena of Cosmos. The general survey of Nature, beginning with the farthest nebulæ, and the revolving double stars of heaven, and coming down to the terrestrial phenomena of the geography of organic beings,

-plants, animals, and the races of mankind-contains the most important and essential portion of my whole undertaking: The intimate connection of the General with the Particular; the spirit pervading the treatment of the subjects of experience discussed; the form and style of the composition. The two succeeding volumes will comprise the discussion of the means that incite to the study of nature (through animated accounts of natural scenery, landscape painting, the cultivation and grouping of exotic plants in the hot-house); the History of the contemplation of the universe, in other words, the gradual comprehension of the idea of the natural forces co-operating as a whole; and the Specialities of the several departments, whose reciprocal connections were indicated in the General Picture presented in the first volume.

I have always separated bibliographical references from the text, as well as evidences of the value of observations, where I have thought it necessary to adduce them, appending them at the end of the several sections. Of my own works, through which, as may be imagined, the facts are variously and widely scattered, I have always referred to the original editions, as it was of importance here to be very particular in the numerical indications, and I am full of mistrust of the accuracy of translators. Where, in rare instances, I borrow short passages or state