meteorological observation; by it, electrical phenomena and the formation of clouds could be observed. The reason why the English meteorologists had failed to make any satisfactory observations, was because they lived on the western side of a great continent, with no opportunity to make observations west of them, while we lived on the eastern side of a great continent, with telegraph lines extending inland thousands of miles. The formation of hail, thunder gusts, tornadoes, and other phenomena, were explained in a clear manner, which was listened to with intense interest and frequent applause.

He gave an account of the method of observation pursued each day at the Smithsonian Institute. They have a map of the United States hung upon a board, with pins stuck through it at the points where the observers of the institute are stationed. The Institute has daily reports by telegraph from many of these points. Each morning an assistant hangs a cord on the pins to indicate the state of the weather-black if raining, green if snowing, brown if cloudy, and white if fair. All storms travel east, and thus they are enabled to predict with great certainty the condition of the weather twelve hours in advance.

Meteorology as connected with agriculture, was then considered. It was shown that the fertility of the soil of the United States was owing to the currents from the Mexican Gulf and the Pacific; and it was shown that the climate of the 100th meridian must forever be unfruitful, unless trees should be planted, which might modify it somewhat.

CORRELATION OF PHYSICAL AND CHEMICAL FORCES.

Professor Joseph Le Conte, of South Carolina, read one of the ablest papers of the session on the above subject. The fact that matter is constantly changing its form, and is also indestructable, it universally admitted. Both these axioms hold good with regard to force. "The same absolute of force exists in the universe at all times and forever. The mutual convertibility of the various forms of force, is called the correlation of forces; and the unvariability of the absolute amount in the midst of changes shows the conservation of force."

There are four planes of material existence, which may be regarded as being raised one above another. The first and lowest is the plane of elementary existence, the second the plane of chemical compounds or mineral kingdom, the third the plane of vegetable

existence, and the fourth animal existence. Now it is apparently impossible for any known force in nature to raise matter through all these grades at once. On the contrary, there is a special force adapted for the elevation of matter from each plane to the one above. It is the special function of chemical affinity to raise matter from plane one to plane two. All the changes too which take place upon plane two by the mutual reaction of bodies situated upon that plane, are under the guidance and control of this force. It is the special prerogative of the force of vegetable life, to lift matter from two to three, or from the condition of mineral to the higher condition of vegetable matter. All the changes which take place upon this plane, the laws of which constitute vegetable physiology, are under the guidance of this force. Finally the force of animal life, and that alone, enjoys the privilege of lifting matter still higher into the fourth plane, i. e. the plane of animal existence. No force in nature can lift from one to three, or from two to four. Plants cannot feed entirely upon elementary matter, nor can animals feed upon mineral matter. The reason of this will be seen in the sequel. Thus it seems that after matter is raised from the elementary to the mineral condition, it requires an additional force of another and peculiar kind to raise it into the vegetable kingdom, and again another accession of force to raise it into the animal kingdom. Thus these kingdoms are truly represented as successive planes raised one above the other thus: 1, elements; 2, mineral kingdom; 3, vegetable kingdom; 4, animal kingdom.

In the same manner as matter may be arranged in several distinct and graduated kingdoms, it seems to me the forces of nature may be properly divided into distinct groups arranged in a similar manner one above the other. These are the physical, the chemical and the vital forces. And as in the case of matter, so in the case of force it is impossible to pass directly from the lowest to the highest group without passing through the intermediate group. The conversion of physical into vital force seems impossible without passing through the intermediate condition of chemical force

The argument of Mr. Le Conte went over wide ground and discussed the de- composition and re-formation of tissues and cells in plants the atomic changes-the conservative forces, showing that vital is only transferred to physical force. In conclusion he asked; "If this is so, is it not possible that physical forces may generate

organisms de nevo? Do not the views presented above support the doctrines of equivocal generation and the original creation of species by physical force? I answer that the question of the origination of species is left exactly where it was found and where it must always remain, viz., utterly beyond the limits of human science. But although we can never hope by the light of science to know how organism originated, still all that we do know of the laws of the organic and inorganic world seems to negative the idea that physical or chemical forces acting upon inorganic matter can produce them. It is true that vital force is transformed to physical force, but the necessary medium of this transformation is an organized fabric; the necessary condition of the existence of vital force is therefore the previous existence of an organism. As the existence of physical forces cannot even be conceived without the previous existence of matter as its necessary substratum, so the existence of vital force, is inconceivable without the previous existence of an organized structure as its necessary substratum. In the words of Dr. Carpenter: It is the speciality of the material substratum thus furnishing the medium or instrument of the metamorphosis, which establishes and must ever maintain a well marked boundary line between physical and vital forces. Starting with the abstract notion of force as emanating at once from the divine will, we might say that this force operating through inorganic matter, manifests itself as electricity, magnetism, light heat, chemical affinity and mechanical motion; but that when directed through organized structures, it effects the operations of growth, development and chemico-vital transformations."

FORMATION OF OCEANS AND CONTINENTS.

Prof. LE CONTE then gave his views in respect to the formation of continents and oceans. It was an attempt to prove the truth of the theory of Prof. Airy as to the laws governing bodies floating upon fluids, and considered as explaining the phenomena of continents, oceans, and volcanoes, upon the supposition that the inside of the earth is fluid and enclosed by a crust. Prof. Le Conte gave an elaborate explanation illustrated by diagrams of different bodies floating upon water, proving that the under surface of such bodies may be judged of as to their configuration by a simple inspection of their upper surface. "If there is a general rising or depression of the upper surface from the margin towards the middle, we may be absolutely sure

there is a general projection or hollowing of the under surface corresponding; in a word, the general outline of the two surfaces is similar." If the surface of the earth is raised by continents, a corresponding thickness or elevation must be found inside, a swelling inward of the crust; and if the outer surface is depressed as in ocean bottoms, there the inner surface is hollowed out, making the middle of the bottom much thinner than the edges. The speaker from the evidence adduced to prove these general ideas, assumed that the centre of the earth was fluid, that the crust floats upon its surface and is subject to the laws of floating bodies. The laws and conditions under which this crust cooled and its state when solidified were then scientifically explained at length, as tending to confirm the generally accepted theories as to the fluidity of the central mass.

This theory, the speaker remarked, would satisfactorily account for the distribution of volcanoes, if not for the phenomena. He admitted that volcanoes were the most difficult of explanation of all the igneous phenomena in nature, and although gases and vapours are probably one cause of the eruptions, yet he thought few physical geologists would admit the local pressure of gas as the only or even the chief cause. The great general cause, he thought, might be the reaction of the crust upon the interior fluid, and gave his reasons therefor. At any rate the disruption of the crust should take place in the thinnest part as the bottom of the sea, and the next place should be the next weakest part or the margins of the sea, and these are exactly the places where the volcanoes occur. Of 225 active volcanoes mentioned by Humboldt, 155 are situated upon islands in the ocean, and of the remaining 70 almost the whole are situated near the sea-shore, while but very few are found in the interior of continents. This paper as a whole was remarkably clear, logical and conclusive, and presented many points worthy of study.

GYPSUM AND MAGNESIAN ROCKS.

Mr. T. STERRY HUNT, of Montreal, showed that besides those gypsums formed by the alteration of beds of limestone, another class, by far the more important, comprehends those gypsums which have been deposited directly from water. Such may be produced during the evaporation of sea-water; but Mr. H. has recently shown that sulphate of magnesia is decomposed by solution of bicarbonate of lime, giving rise to gypsum, which is first deposited, and a

more soluble bicarbonate of magnesia, which by further evaporation is separated as hydrous carbonate, either alone or mingled with carbonate of lime. When these magnesian precipitates are gently heated under pressure they are changed into magnesite or dolomite. Thus are explained the magnesian rocks associated with gypsums and with rock salt. The action of solutions of bicarbonate of soda may in like manner separate the lime from sea-water and give rise to solution of bicarbonate of magnesia; in this way are formed the magnesian limestones which are not associated with gypsum. The intervention in this process of the waters of alkaline metalliferous springs will explain the metalliferous character of many magnesian rocks. The source of the bicarbonate of soda has been the decomposition of feldspathic rocks to form clays and clay slates. The action of this alkaline carbonate upon the lime and magnesia salts of the primitive sea has been the source of limestone and dolomites, as well as of the sea salt which we find in the ocean, at the same time that the intervention of the carbonic acid of the atmosphere which has been through the medium of the soda, fixed in the form of carbonate of lime, has served to purify the air and fit it for the support of higher orders of plants and animals. In this relation between the atmosphere, the argillaceous rocks, the limestones and the salt of the sea, we have a remarkable illustration of the balance of chemical forces in inorganic nature.

FORMATION OF SILICIOUS ROCKS.

Mr. STERRY HUNT then spoke of sediments resulting from the disintegration and chemical decomposition of quartzose, feldspathic and pyroxenic rocks. In these the coarser portions consist of quartz and of feldspar containing potash, while the finer clays have less silica but more alumina, and besides alkalies lime, magnesia and iron, which are rare in the coarser sediments. These latter being more pervious to water, the small portions of soda, lime and magnesia still remaining are removed by lixiviation, while the clays retain these bases. When these different sediments are altered and crystallized we shall have on the one hand granitic or trachytic, and on the other pyroxenic rocks, the two great types recognized in igneous rocks, all of which Mr. regards as derived from the alteration and fusion of sedimentary strata. To the gases and vapors evolved by the fusion of deeply buried strata are to be referred the phenomena of earthquakes