I suffered severely from a single day spent amongst the pure snows of the highest summits. 2. On the photometric effect of the diffuse light reflected from the sky, Professor Kämtz first, I believe, announced the startling fact, that half the photometric effect of Leslie's instrument is due to the diffuse light of the sky, the other half only being the effect of the direct rays of a bright sun. This singular paradox also manifests itself by the fact, that cloudy weather, if the sun be not itself greatly obscured, apparently increases the effect of the solar radiation. Of the truth of both of these facts, I had also last year sufficient evidence, of which I shall quote one or two examples. On the 28th June 1842, a warm and clear day, at 6000 feet above the sea, at 1h 40m. The photometer in the sun placed on the snow, stood at 121° An alpine pole, an inch in diameter, was then stuck into the snow, so as to throw its shadow on the instrument, thus intercepting the direct sun-beam only. It fell to 82° 39° Leaving for the direct effect of the sun-light, the remaining 82° being derived from the reflection of scattered sky-light, and from the snowy surface. At the same place and time, the photometer, in the sun, surrounded by grass, stood at Shaded by a stick as before,. Direct sun effect,* 78° 30° 8 Now, if we look to 78° as the total effect of the sun's light and its reflection from the ground, in one of the hottest days of June, in a fine climate and 6000 feet above the sea,―it appears to be inconceivably small, when we know that the same instrument often stands at 120° in moderately fine weather in Scotland. What is the reason? The sky does not reflect so much light when it is pure as when it is milky, and its surface being immense, compared to the apparent surface of the *The difference of this and the last is probably due, in a great measure, to the defect in the principle of the instrument, the momentary increment of heat necessary to maintain the temperature 1° above 120°, being greater than what is necessary to maintain it 1° above 77°, for example. There are likewise other sources of error. sun (100,000 times greater), a small addition to its reflective power increases the photometric indication more than the thin haze of vapour which produces that effect diminishes the direct sun-light. Again, on the 29th June, a clear and warm day, in the same position at 11 a.m.— The photometer standing on snow, Direct sun effect, 114° 63° 51° I never observed these effects so strongly as on the 30th of June, a day of the most intense solar heat, when, at a height of 7600 feet, the sky exhibited a deep indigo tint, unusual for that moderate elevation. I was engaged for some hours in making trigonometrical observations, on an exposed promontory of rock, with scarcely any shelter from the piercing sunbeams. At length I was so exhausted as to be obliged to thrust my head now and then behind a stone for protection and relief. Now, at this time, the photometer directly exposed on the rock to the sun, stood only at When shaded from the direct sun-beam, it fell to 88° 22° the smallest result for diffuse atmospheric radiation and reflection from the soil combined which I have witnessed. This, it will be observed, leaves for direct sun-heat, 66° which is large, compared with the previous results. It is certain from these experiments, that the photometric effects thus measured bear no kind of proportion to the physiological effects of direct and reflected heat.-Prof. Forbes's Travels through the Alps, p. 416. On the Progress of Ethnology. By Dr HODGKIN. (Communicated to this Journal by the Society.*) Read before the Ethnological Society, London, Nov. 22, 1843. The study of man, in its most extended sense, to which the term Anthropology is fitly applied, is a most complicated subject, presenting such various points that it admits of being divided into several departments, each of which may constitute or appertain to a separate science. The physical conformation of man, and the consideration of the functions of his several organs, come within the province of the comparative anatomist and physiologist. As an intelligent being, man is a subject for the metaphysician, and, in his compound character of an intellectual animal, is the object of contemplation and study for philosophers of various sects. Some, like Cabanis and Hope, may take a comprehensive view of the whole. Others treat of his progress individually in relation to his education and unlimited capability of cultivation. Others pursue the subject in relation to man as a gregarious animal, and are consequently occupied with the different branches of political economy, social government, and the like. Man is also studied in relation to the lapse of time in which his race had existed; hence the group of general or particular historians. Researches of these and analogous descriptions have exhibited man individually and collectively in so great a variety of conditions, as to render it a matter of special inquiry how and to what extent he may be influenced by the circumstances in which he is placed; individually as to diet, climate, mode of life, and inherited peculiarities, collectively by government, religion, influence of surrounding nations, and dominant prejudices whence soever derived. Lord Kames, Falconer and Herder, may be mentioned amongst the investigators of these points. *The Ethnological Society of London is formed for the purpose of inquiring into the distinguishing characteristics, physical and moral, of the varieties of mankind which inhabit, or have inhabited, the earth; and to ascertain the causes of such characteristics.- EDIT. When all these various subjects are more or less carefully viewed and considered in relation to man as an animal of a peculiar kind, it may very naturally be inquired, are all these differences to be ascribed to modifying circumstances acting upon beings essentially similar and of the same stock? Prichard and Lawrence put the supposed case of a previously uninformed individual seeing in contrast the extremes of colour, and the extremes of civilization and barbarism, by which he would almost necessarily be led to infer absolute distinctness of species. Lord Kames had previously stated that a similar inference must be drawn, were not the declaration of Scripture opposed to it. Investigation of the innumerable and almost insensible gradations between these extremes, might as naturally induce the opposite idea, which is actually embraced by many of the best inquirers. Irrespective of these extreme views, writers of the highest antiquity have spoken of man as formed into various distinct groups which have been known as separate nations; some distinguished by their languages, some by their colour, and many by their country, of whom it has been merely known that they inhabit such a territory and possess such and such peculiarities of custom. Facts of this kind are necessarily blended with the writings of historians and geographers from the most remote period down to the present time, and whether separated into a distinct study or not, the description of them has acquired the peculiar and appropriate name of Ethnography or the description of nations. With the object of exhibiting the mode in which the human race, broken up into more or less distinct groups, is distributed over the face of the globe, various attempts have been made to give the geography of man, just as we have the geography of plants by Humboldt, the geography of insects by Latreille, and the geography of crustacea by Milne Edwards. Thus we have the geographical distribution of man attempted by Zimmermann. Various Ethnographical maps, of greater or less extent, have been produced in this country and on the Continent, and a comprehensive scheme for the production of an ethnographical map of the world has been projected and commenced by Mr Greenough, of which, it is enough to say, that in design and in the collection of materials, it is well worthy of the author of the geological map of England. Were the differences which are observed in mankind wholly the result of physical circumstances, we might expect that an ethnographical map of the world would exhibit peculiarities and physical characters bearing some relation to the parallels of latitude, or rather like the isothermal lines and the regions marked by the production of peculiar classes of plants, shewing the combined influence of latitude and elevation. That such is not the fact is abundantly manifest, although much of the materials for the construction of such a map remain to be collected. It is so far from being the case, that we find every shade of colour, from the white to the deepest black, in the same parallels of latitude, and even in juxtaposition with each other. We may further observe, that the individuals presenting these different characters, are very differently affected by the climate to which they are exposed. Are we hence to infer absolute distinctness of race, the one adapted to one climate and the other to another; as the tropical palm is distinct from the northern pine? Such a difference, however plausible it may at first appear, is by no means necessary, since it is equally consistent with probability to suppose that the descendants from one original stock, may, through a succession of generations, have become more particularly adapted for certain climates, which result being produced, the influence of a different climate cannot be equally tolerated; just as the metal iron, according to the particular mode in which it is treated, may be rendered ductile or brittle on the application of heat, and the varieties so produced cannot afterwards be mutually substituted for each other. These and numerous other difficulties have presented themselves to the consideration of those whose attention has been turned to the various conditions and appearances in which man is found on the surface of the globe. The study of this very interesting subject forms a branch of science, to which the name of Ethnology has been given. As I have heard remarked by the great Cuvier, with regard to Zoology in general, so in this particular branch of it, it is obvious |