WELLINGTON PHILOSOPHICAL SOCIETY.

New Zealand Times, Volume XXIX, Issue 4166, 28 July 1874, Page 3

WELLINGTON PHILOSOPHICAL SOCIETY.

The President’s Annual Address. Tlio following Paper was read by Dr. Knight, the President of the Wellington Philosophical Society, on the 18th instant. It has been the custom for your Presidents in their annual address to notice the paper's discussed at the Society’s meetings during the year. I find it difficult to make such notices interesting. Indeed, it is the most valuable papers that are the most difficult to comment on, except in general terms of praise. Take Mr. George’s paper on the Patent Slip at Evans’ Bay—the first of our papers in the Transactions of the Institute —it is over-running with valuable suggestions for Engineers ; or turn to the end of the volume, wo have Captain Morseby’s Lectux'e on New Guinea; certainly, in this last case I may tell you that Dr. Maclay visited the Astrolabe Gulf in the years 1871 and 1872, and studied the inhabitants of the whole coast of that Gulf, and the dwellers of the islands near Cape Dupcrro, and speaks of them, as Captain Morseby did of those he met, as living a life of such perfect happiness that ho called the islands “ The Archipelago of Contentment.” As regards the characteristics of races, it may be interesting to note, in connexion with Captain Morseby’s description, that the Papuans have the upper teeth projecting considerably beyond those of the lower jaw, and, contrary to - what is usually stated, there is no such roughness of the skin as would constitute a race characteristic. The colour of the skin, too, is in general of a chocolate brown—not of a blneish-black colour, as has been previously asserted; and the hair of the head is not naturally disposed in tufts or clumps, but grows just as it would upon the head of a European. Mx - . Galton, from whose review I have culled the above remarks, completes the picture by observing that the Papuan maidens begin, even at the tender age of seven years, to cultivate the art of which Mr. Turveydrop was the distinguished Professor. You will find at page 391 of the Transactions for 18 /3, a short notice of a discussion on Solar and Ten-estxial Badiation, introduced by Mr. C. E. Marten, who explained that the Black Bulb Thermometer in Southland frequently ranged as high as 170°, being 30° higher than in Sydney, and much higher than it has ever reached in the North Island. As some doubts are implied in the printed report of the correctness of the readings, I wish to state that Mr. Marten is not only an enthusiast in meteoroligical pursuits, but a most painstaking observer, with whom my duties as first Director of Meteorological Stations in New Zealand brought me in very pleasing communication. As this is a ' subject on which I formerly took much trouble, and may claim for mvself the merit of having established all the principal Meteorological Stations in New Zealand, and as it was a great comfort to have the co-operation of Mr. Marten, I am anxious to explain why I the observations referred to are correct. Of course we all know how difficult it is to prevent ‘-'cooking” of observations. In looking over my correspondence with a distinguished savant who had a great deal to do with getting up meteorology in India, he notices how discouraging it was to wox - k at the results of people who had no training in the use of instruments. The stupidity of some observers is impregnable. An intelligent, well educated man, sxxpplied him a long sexies of wet-htili observations obtaixxed by holding a thermometer under ivater and reading ofl—the bxxlb was wet, what more could be wanted ! Yoxx will understand, then, the comfort, in starting a number of Meterological Stations, of having a Member of the Meteorological Society of England for a coadjxxtox-. I did not join in the discussion, further than to inquire what was the vapour tension at the time those high indications of the Black Bxdb Thermometer were taken. I shall explain why I asked for that information. The Black Bulb Thexmometer is always exposed, for observation, to the direct rays of the sxxn. The calorific x - ays of the sxxn pass through air devoid of aqueous vapour with no appreciable loss; but if water in the foxm of invisible vapour be present, the air is not pei'fectly transparent to those rays, and offers, I believe, a slight obstrxxction to their nassa"e. It is almost opaque to radiant heat from the surface of the ground. Transparency to heat and light is witnessed in the passage of the sun’s rays through the glass windows of our The heat in a close room into which the sun shines may be overpowering, while the glass, through which the whole of the heat has passed, remains cold. The greater the proportion of aqxxeous vapour the more solar heat is absorbed in its transit through the atmosphere. Now the quantity of vapour in the air- depends nxainly on temperatxxre. In the colder regions of the Soxxth, although the air- may be saturated with vapour, the relative proportion of vapour* to aix’ is mixch less than in tx*opical climates ; and thus it happens that in Southland less of the sun’s heat is lost in its passage to the earth. For instance, —the quantity of vapour in air- at a temperatxxre of 90° Falxr., is four times as great as in air at 50° Fahr.; and the consequence of its being loaded with vapour at the higher temperatxxre is a slight obstruction of the passage of the sun’s rays; and were it not that they , strike in Southland with a somewhat greater obliquity than in Sydney, and. thus traverse a greater mass of air, it is possible that these high readings of the Black Bulb Thermometer woxrld more frequently happen in the southern parts of the Middle Island. Dr. Hooker-, in his observations on the climate of the Himalayas, states that at a height of 10,000 feet at 9 a.m. in the middle of summer the thexmometer mounted to 132° Fahr - . in the sun when the tempex-atux-e of the air was 32° Fahr., a difference of 100°. This difference no doubt would have been much gx-eater had the blade bxdb been px-otected from cux-rents of the srrrroxtnding cold aix-, and had it lain on a bed of black cotton-wool. Tyndall quotes this for the purpose of showing that the extraordinary difference of 100° can only be accoxrnted for by the sxxns rays passing through aix- almost devoid of aqueous vapour as through a vacuum. Dr. Hooker found the same extraordinary difference on the plains of India, because of the dryness of the air; but no such result bad been found in Calcutta, where the heated atmosphere is surcharged with aqxxeous vapoux-. Tyndall goes on to say that he himself “never, under any circumstances, suffered so much from heat as in descending on a sunny day from the Cox-xidor to the Grand Plateaxx of Mount Blanc. The air was perfectly still and the sun litex-ally blazed against him and his friend. Though hip deep in snow, still the heat was unendurable.” What I contend for is, that in high latitudes the air does not contain the same quantity of aqueous vapour as in warmer latitudes. That the presence of aqueous vapour interferes in a slight degree with the passage of solar heat, and this slight obstruction affects the black bulb so as on rare occasions to render tlxe x-eadings no higher in Sydney than in Southland. And I may add, as a “xider” to the above, that those who coxrtexrd that the atmosphere, whether charged with vapour or not, is a vacuum to the sun’s heat rays, are left with no explanation of the Ixoat .being diminished when that luminary is low down in the heavens.

In connexion with the Meteorology of Now Zealand, I wish to offer an explanation of the Hot Winds of the Canterbury Plains, iho N.W. dry, hot winds of Australia, in their over the ocean, become surcharged with vapour at the expense of a noticeable part of their heat. In the philosophic language of the day, the heat of the air is made to do work by converting water into vapour, and by maintaining it in that state. The sensible heat thus absorbed by vapour is converted into latent heat —that is, the heat is not lost, but is engaged in the veiled work of maintaining water in an invisible state. The air in thus dissolving water becomes a carrier, or distributor of heat. It is not difficult to give an approximate estimate of the quantity of heat sensible to the thermometer by the reconversion of vapour into water, iho problem has been solved by experiments, and it is found that the of heat stored up in aqueou vapours from one pound of water is sufficient to heat lOOOlbs. of water one degree of Fahrenheit, or, as Tyndall puts it, to fuse bibs, of cast iron. Next as to the phenomena arising out of the fall of heavy rains on the flanks of the ranges on the West Coast. The quantity of heat liberated would be considerable did not other causes interfere with its escape. The rain itself carries down with it a small part of the sensible heat, but the greater portion of that set free is at once taken up by the atmosphere in rising to the altitude of the lofty ranges in its passage to the plains of the Middle Island. The sudden rarefaction is duo to the loss of pressure of the column of air lying between the level of the sea and tho average height of the ranges. This dilatation is accompanied by wbat used to be termed an increased capacity for heat, so that heat is absorbed by the air itself. This too, in tho current phraseology of tho day, is called work done at the expense of heat. So that altogether wo have a diminution of sensible heat, but not an actual loss of heat, by tho passage of the air over tho ocean, and next by tho rarification of air in its ascent to tho higher regions of the ranges. When air expands by reason of tho loss of pressure tho undulations of tho of air, which wo terra heat, diminish also—or, in other words, the amplitude of tho vibrations is diminished, and tho distance between tho undulations

incx-eased. Motion imposed on the molecules of matter woxrld go on forever, just as any motion imposed on a mass would never cease, if there wex-e no medium to which it could communicate its motion to other bodies, ox- in some other* way exhaust itself. This inex-tia belongs to molecules as much as to masses. Wlxile the swing of tlxe molecules is diminished, and the distance betweexx the xxxrdulatioxxs. is iircx-eased, the actual force, which we call heat, remains xrndirainished. It is only necessary that the undulations should be again crowded together in order that the exrergy may be restored. So far I hope that I have made my meaning clear, —that air in taking up moxstux-e loses sensible heat. No one who has tx-avelled on the West Coast of the Middle Island can have failed to notice when he leaves the forest road, and comes on the dreary sands of the coast, with a moderate sea breeze, how miserably cold the air is in the immediate vicinity of the breakers. This is owing to absorption of sensible heat by the solutioxx of the spray in the current of air sweeping over the sea. Next, in reference to the heat gained, if any, in the passage of the air over the, extensive elevated regioxx between tlxe West Coast and the Canterbury Plains. The air on the moxxntain ranges gains no addition of temperatxxre from the direct radiant heat of the sun, for the rarified air is, to use a technical expression, almost transparent to the sun’s heat rays— —it permits them to pass with very slight loss. The sun warms the m-oxxnd but not the air. It is not so, however-, -with the heat radiating from the surface of the ground—this is almost exxtirely absorbed'-by the atmosphere, which thus gains sensible heat xxntil at length it reaches the eastern slopes of the moxxntain ranges. Here, where the colxxmxx of air begins its descent to the plains, we oxxo-ht to have a complete reversal of every phenomena that accompanied its passage fx*om the level of the sea on the AYesb Coast till it x-eaches the elevation’ of the mountain ranges. As the column of air sinks down, the increased extent of the vertical column gives incx-eased pressure, and compresses mox*e and mox*e the lower* statxxm—the latent heat becomes sensible and the thermometer rises. But it is necessary that I should give yoxx hex-e some proof that incx-eased px-essxxre adds to tlxe energy of heat in aeriform bodies, ox-, in the old, expx-essive phraseology, convex-ts the latent heat into heat recognised by oxxr senses, and registered by the thermometer-. Airy has explained that when the changes of volume and pressure ax-e very x-apid, the chaxxges of tempox-atxxre of .the aix- ax-e very great: “ Upon suddenly condensing air it becomes very hot. Wo have verified the experiment, that if inflammable tixxdex- is placed in the bottom of a cylinder* in which a piston fits tightly and slides easily, when the piston is driven x-apidly down so as to condense the air- very much befox-e it has time to impax-t the whole of its heat to the sux-x-oxxndixxg metal, the air will inflame the tinder." And Airy remarked, “in the powerful airpumps (driven by large steam engines) which were used to exhaust the air txxbes upon the Atmospheric Bailway, that when the attenuated air in the tube, having acqxxix-ed the temperature of the groxxnd, was compressed by tlxe operation of pumping so as to be able to open the last valve in opposition to the pressure of the atmospheric aix-, the emergent air was so hot as to be unbearable to the hand. If the heated aix-, without having lost caloric, be allowed to expand to its fox-mex- dimensions it exhibits its fox-mex- temperatux-e ; that is, it cools by sudden expansion. Axxd this is so well known that it has been proposed to sxxpply apartments in hot climates with cool air, by compressing air in a close vessel, allowing the increased heat to escape by contact of the vessel with the external aix- ox- neighboux*ing sxxbstanccs, axxd then pex*mitting the condensed aix- (at the atmospheric temperature) to expand into the apartments, when it would have a much lower teinpex-ature. You see at once that the condition of the aix- in tho tubes of the Atmospheric Kailway beax-s the closest relationship to what takes place in the transit of the aix- from the West to the East Coast. hirst, the rarefaction of air in the tubes ; —this represents the expansion of air in its ascent to the mountain ranges. The subsequent compression of aix-, fox* raising the escape valve is analogous to the descent of the colxxmxx of aix* from the ’ ranges;—and the escape of the hot aix* at the valvxxlaxopening is a counter-part of tho heated aix- sweeping over the Canterbury Plains.

A, Paper on. tlie Preservation and Treatment of the Timber of New Zealand, by Mr. Buchanan, of the Botanical Department, is deserving of some notice. The forests of New Zealand are cut down recklessly at all seasons of the year j and when the trees are sawn into square timber or planks no attempt is made to preserve them against decay and deterioration. Greater attention should be paid to seasoning. lam doubtful whether we do not, however, attach too great importance to the tune of the year in which the trees are felled. If cut down in the summer they should be allowed to lie where they are felled, and no branches cut ofl, so that the sap may be dried oft’ by evaporation from the surface of the leaves. Unless this be attended to, the timber from trees cut down in summer and immediately sawn up, will be much deteriorated in value—the planks will warp and the larger timber will split and spoil from hasty drying. On the whole, it is safer that the trees should be cut down, or killed by “ ringing,” during the winter months. As soon as possible after being felled they should bo cut into scpiare timber and planks, and these stacked in a proper manner, and carefully protected, from the sun’s rays. Timber so cut, seasoned, and protected, might be branded as a guarantee to purchasers. The letter of the brand would show the year in which the timber was felled, just as silver plate is lettered to show the year in which it was stamped. With respect to ringing trees which exude largo quantities of gum from the cut surfaces, I am decidedly of opinion that the loss of gum would be followed by a loss of power in the timber to resist decay, and that in such instances “ ringing” is objectionable. One great advantage of charring the lower end of posts is, that the sap is dispersed at that end. If, in addition to charring, the heated end is immediately plunged into cold tar, made more liquid by the addition of kerosene, I think the post below the ground would be almost indestructible. The moisture left in the charred end, when the post is first removed from the fire, would be in form of steam, and on its condensation by the cold of the tar bath in which it is plunged would produce a vacuum into which the tar would be forced by atmospheric pressure. I may mention that careful experiments have been made in the United States of America by Generals Cram and Gillmore, and the result of their investigations is, that Seely’s process is the best. It consists in subjecting the wood to a temperature above the boiling point of water and below 300 ° Eahr., while immersed in a bath of creosote a sufficient length of time to expel the moisture. When water is thus expelled the pores contain only steam; the hot oil is then quickly replaced by a bath of cold oil, by means of which change the steam in the pores of the word is condensed and a vacancy formed, into which the oil is forced by atmospheric pressure and capillary attraction. I find that in California they are already alarmed at the rapid destruction of their forests, containing the largest and finest trees in the world. It is estimated that one-third of all the available timber has been consumed, and that the whole of the available timber will bo consumed in 20 years. One of the worst features of the settlement of new countries is the reckless way in which the timber is destroyed. Not only is the practice condemned in severe terms by thoughtful men in California, but the opinion must be gaining ground that the State should interfere. The only remedy seems to them to be for the Legislature to take up the matter, and by proper laws to provide not only for the Preservation of the Forests, but for the planting of trees pari pasm with the settlement of the country. It is maintained by writers on the subject in America, that at least one-third of the surface of any country should be forests—that this proportion between clear land and forests is one which will secure the greatest results in an economic point of view. It is also insisted upon that a fertile country, if stripped of its forests, may be half overwhelmed by desolation from the consequent change of climate. That in fact a country so denuded of rain-gatherers is either dried up in summer or the soil is washed off from the hill sides by the heavy rains of winter. Marsh speaking of the destruction of forests upon the different countries of the earth says :—“ There are parts of Asia Minor, of Northern Africa, of Greece, and even of Alpine Europe where the operation of causes set in action by man has brought the face of the ■earth to a desolation almost as complete as that of the moon. The destructive changes occasioned by the agency of man upon the flanks of the Alps, the Apponines, the Pyrenees and other mountain regions in Central and Southern Europe, and the progress of physical deterioration, have become so rapid that in some localities a single generation has witnessed the beginning and the end of the melancholy revolution.”

I know no sight more sad than to witness tho destruction by five of forests on the hill sides—those mournful streaks sweeping along the more accessible sides of tho ranges, with blackened trunks like Banquo's ghosts here and there in the midst—without parallel the most melancholy spectacle of wasteful destruction. I have doubts of the

probability of much immediate good being effected in tlio way of planting in the permanent settled districts of the Colony. But there can be no doubt of our power to stay the destruction of forests on the ranges and on other lands not well adapted for agriculture. Here we have unquestionable means not only of staying wanton destruction, but of securing the successional grown of trees to make good the full grown timber, when removed. To plant land with valuable timber is a slow process—■ to preserve what we have is surely our duty. It is on the ranges and highly broken ground that the timber is most effective in ameliorating a climate and of feeding the streams from which the plains may be irrigated. The most interesting of our Papers is that of Dr. Hector on the huge Fossil Reptilian Remains lately discovered in the Southern Island. That memoir has a value for all time. As a contribution to the knowledge of those enormous reptiles it will certainly engage the careful study of scientific men both in Europe and North America. Contemporaneous with these discoveries we find, from the report of Cope, that similar' skeletons of these monsters of the ancient seas are being found in the cretaceous strata of the Kansas, in North America. “ If the explorer of these plains” (on whose level surface, denuded of soil, may be found huge oyster shells not less than 2 feet across, some opened, like remnants of a half finished meal of some titanic race, who had been frightened from the Board never to return,) “ searches the ravine he will,” says Cope, “ come upon the fragment of a tooth or jaw, and will generally find a line of such pieces leading to an elevated position on the bank, where lies the skeleton of some monster of the ancient sea. He may find the vertebral column running far into the limestone that locks him in his last prison ; or a paddle extended on the slope as though entreating aid ; or a pair of jaws lined with horrid teeth, which grin despair on enemies they are helpless to resist; or he may find a conic mound on whose apex glistens in the sun the bleached bones of one whose last office has been to preserve from destruction the friendly soil on which he reposed.” The Leiodons, parts of whose skeltons are seen in our Museum, were of enormous length, varying from 30 to 100 feetj “ their heads were large, with eyes partly directed upwards; they were furnished with two pairs of paddles like the flippers of a whale ; they were furnished with formidable teeth for seizing their- prey.” The physiognomy of the giant species in our collection, was rendered peculiar by a long projecting muzzle. Cope once found the “wreck of an individual of the Leiodon proriger strewn around a sunny knoll beside a bluff, and his conic snout pointing to the heavens formed a fitting’monument, as at once his favorite weapon and the mark distinguishing all his race.” And here I must quote from Cope a peculiarity of these creatures by which they are unique among animals, but which I do not see alluded to in Dr. Hector’s elaborate report. Nor can I satisfy myself that it could have existed in the reptiles whose fossal remains are in our Museum. “In swallowing their prey like snakes, they were without that wonderful expansibility of throat, due in the latter to an arrangement of levers supporting the lowerjaw. Instead of this each half of the lower jaw was jointed nearly half way between the ear and the chirr. This enabled the jaw to make an angle outwards and so widen by much the space enclosed between it and its fellow. The ends of these bones were in the Pythonomorpha only bound by flexible ligaments. The outward movement of the basal half of the jaw necessarily twists hr the same direction the “ quadrate” or-colurnn-like bone to which it is suspended. The peculiar shape of the joint by which the “ quadrate” bone is attached to the skull, depends on the degree of twist to bo permitted, and, therefore, to the degree of expansion of which the jaws were capable. As this differs much in tiro different species, they are readily distinguished by the “ quadrate” bone when found. There are some curious consequences of this structure, and they are' explained as an instance of the mode of the reconstruction of extinct animals from slight materials. The habit of swallowing large bodies between the branches of the under jaw necessitates the prolongation forward of the mouth of the gullet j hence the throat of the pythenomorpha must have been loose and almost as baggy as a pelicans. And the tongue,” continues Cope, “must have been long and forked, and fortius reason, its position was still anterior to the glottis, so that there was no space for it except it were enclosed in a sheath beneath the windpipe when at rest, or thrown out beyond the jaws when in motion. Such is the arrangement in the nearest Irving forms and it is always in these cases cylindrical and forked.”

The transactions of the New Zealand Institute shew by numerous Papers how actively the minds of our Geological friends are engaged on the subject of the Glacial Period. It is the fashion of the philosophy of the day to ascribe much of the moulding of our hills and valleys to the denuding power of ice—more in fact than one is inclined to admit. Professor Phillips at a late meeting of the British Association remarked, that one is almost frozen to silence in presence of the vast sheets of Ice, which some of his friends, followers of Agassiz, believe themselves to have traced over the mountains and vales of a great part of the United Kingdom. He refuses to accept the proposition that these “ ice-rubbers” plough out the valleys and lakes, until we possess more knowledge than has yet been attained, regarding the resistance offered by ice to a crushing force, seeing that under a column of its own substance 1000 feet high it would not retain its solidity. I have alluded to Phillip’s opinion, because I see in Giekie’s late work that reference is made to the fact, that from the foot of glaciers in Greenland, streams of water issue and unite to form considerable rivers, one of which, after a course of 40 miles, enters the sea with a mouth nearly of a mile in breadth—the water flowing freely at a time when the outside sea was thickly covered with ice. This flow of water, Giekie thinks, probably circulates to some extent below every glacier, and he accounts for it by the liquefaction of ice from the warmth of the underlying soil. I am sure you will find a more natural solution of this flow of water from glaciers—estimated not less than 3000 feet thick—in the suggestion first made by Professor James Thompson, and subsequently proved by his brother Professor W. Thompson, that the freezing point of water is lowered by the effect of pressure 0.23° Fuhr., or about of a degree for each additional atmosphere of pressure. Now a sheet of ice 3000 feet thick, is equal to a pressure of 83'atmospheres, at which pressure it would require a temperature of 19° below freezing point to retain the form of ice. In the state of running water below the glacier, it might readily, as Giekie states, absorb heat from the underlying soil sufficient to retain its liquid form, as the overlying weight gradually lessened at the edge of the glacier. In this too,' we have a safe assurance that these enormous thicknesses of glaciers can exist only where there is scarcely any or no inclination of the land to the sea board, and that no sheets of ice of such enormous thickness could possibly exist on the sides of mountains, as they would have between them and the mountain side a stratum of water; and to use a common expression would come down “ on the run.” And this may well make us hesitate to adopt with Giekie the views of the Swiss Glacialists, who, I gather from Giekie’s late work, speak of sheets of ice having existed in the groat Ice Ago, not less than 3000 feet thick, overtopping the Jura, and stretched continuously from the Rhine Valley; and Giekie, adds, that no one can believe that this great glacier stopped on the Banks of the Rhine. I do not deny that sheets of ice 3000 or 5000 feet thick exist. I shall maintain, however, as an established fact, that ice if at the temperature of 32° Fahr. throughout, cannot support a column of its own substance 3000 feet high. Nevertheless, a sheet 3000 feet may exist, although the temperature at the surface of the ice is only 32° Fahr., but in this case the temperature at, the base cannot be higher than 13° Fahr. I will explain myself. The specific heat of water is far greater than ice. One pound of ice at 32° Fahr. mixed with one pound of boiling water gives 21bs. of water at 51°; so that 71 degrees of heat have been lost in the more conversion of ice into water. We thus see that every pound of ice converted by pressure into water, demands a large supply of caloric, as a necessity of its change of condition, and absorbs it instantly from the ice in contact with it above. The ice in the immediate vicinity of the layer of water, hardened by loss of caloric, stops for the moment the further conversion of ice into water. But this state of matters continues only momentarily, the ice below, in its turn, robs the ice above of caloric, and this softened, is unable any longer to bear the ■pressure, and flows away as water; and so the ]iroccss extends, until a regular gradation of temperature is progressively but uniterruptedly established throughout the mass, and an equilibrium formed between the forces by which the sheet of ice maintains a fixed altitude. That is, we shall have a gradual fall of temperature from 32° on the surface to 13° at the base, the latter degree being the temperature at winch ice will sustain a column of 3000 feet. I further maintain that no such column as 3000 feet can continue at that height for an indefinite time, unless the temperature of the air is much lower than 32°, because the temperature, if higher than 13°, would gradually creep down to the base of the column of ice, where the lowest stratum would continually melt away in the form of running water. And wo thus see as a necessity of the case, that all thick glaciers have running streams at their foot. I have brought tliis under your notice this evening, because no satisfactory explanation has hitherto been giving of the cause of running

water at the foot of glaciers, nor how it is that sheets of ice 3000 or 5000 feet thick are enabled temporarily to maintain their thickness. Dr. Haast, Mr. Travers, and Captain Hutton, have given much interest to the subject. The origin and formation of the Canterbury Plains have led to the discussion. Captain Hutton has come to the conclusion that the formation of the Canterbury Plains is due to the action of the sea. His argument is, that the Plains rise gradually from the sea board with a gentle slope—that in places they warp round the spurs of the hills at the same level—and that no engineering power could form such level and extensive plains with their beds of water-worn shingle, but the ocean itself. That the singular fact that the Hurunui and Canterbury Plains are on the same level, is, in hi s opinion, an irresistible proof of the correctness of Ms views. I need scarcely add that if this view be correct there has been an elevation of the land of about 2000 feet. Dr. Haast, on the other hand, assumes as sufficient for his views that glaciers of enormous size have moved down from the mountain ranges, and ploughed from the mountain sides the drift with which they have covered the more insignificant hills and formed the plains. That when the glacier outlets ceased to flow and to deposit any more boulders and gravel, the rivers cut through the deposits until they reached the harder rock on which the deposits reposed. The necessities of this explanation require the admission, that a glacial period formerly existed in the Southern Hemisphere—such as is generally admitted to have once existed in the Northern Hemisphere. The weak point of Haast’s theory is, that it does not account for the distribution of the drift so as to form regular plains. It seems to me impossible to confound the irregular pell-mell deposition of glacial drift with the evident stratification, through the agency of water, which exists in the Canterbury Plains. And I observe that Jukes, speaking of the glacial deposits in the low lands of Scotland and Ireland, and in the northern parts of England, even as far south as the northern margin of the Thames Valley, states that he has not the slightest doubt that they were stratified under the sea, notwithstanding the absence of sea .shells from the greater part of them. Mr. Travers objects to Dr. Haast’s assumption of a glacial period, because of its remarkable character, and because we have no evidence whatever that such a change of climate as tMs supposes ever took place. Mr. Travers thinks it more reasonable to conclude that a great elevation of the Middle Island above its present level would give a climate sufficiently cold. An elevation of the Middle Island of about 4000 or 5000 feet would, in Mr. Travers’ opinion, give a climate quite as cold as that assumed for the glacial epoch. The exigencies of these theories require either a change of climate to something like the cold of Greenland, which would satisfy Dr.' Haast’s requirements, or a great elevation of the land. Of course, when we use imagination in scientific matters we have sometimes to draw liberally on Nature for support; and Mr. Travers’ theory has an elasticity about it, fox - , if we object to an elevation of 5000 feet as insufficient, we might double the elevation without being unreasonable. The strength of Captain Hutton’s views springs out of the fixet that he summons to his aid the great leveller and engineer—the Sea, with its never ceasing waves grinding the rocks into sand, and fasliioning the boulders,- and assorting the materials brought to it, either by the glaciers themselves or by the rivers flowing from the mountain ranges, and spreading them out in vast plains. Everything seems to show that plains of any extent arc the result of the action of the ocean, or of vast inland seas. I do not question the statement that terminal Moraines attain great size,, and form mounds of rough angular fragments and debris, —perhaps some hundreds of feet in height. Those are the wastes of the mountains. What I contend for is, that nowhere is this confused debris scattered far and wide and levelled out into strata, forming plains of great extent by the action of glaciers. Captain Hutton admits that the glaciers of the Middle Island have been at some former time of much larger dimensions than they are at present, and that there may have been a glacial epoch in the Southern Hemisphere. But he does not admit that such an epoch bears any relation to, or was contemporaneous with that of Europe. He would refer it, if it ever existed at all, to a period long antecedent. At the same time he guards himself by stating that we have no proof of a change of climate; and as he considers an elevation of the land of about 3000 feet would be able by itself to account for a great extension of the glacier system, thei'e is no necessity of calling in the aid of any other cause. The existence of a glacial epoch must not be denied here. It is a settled question among Geologists that many of the changes on the earth’s surface are due to it. If lam not encroaching too much on your patience I will explain why I do not think we are justified in objecting to Dr. Haast’s assumption of a glacial epoch in the Southern Hemisphere on the ground that it is of a very remarkable character, and as being supported by no evidence whatever; at any rate he follows in the wake of great men. We find Professor Agassiz startling the geological world by his strong opinion that a gigantic glacier once filled the entire valley of the Amazon, and he invited the members of the Alpine Club to go out and search for traces of glacial action on the mountains of Ceand; and I see by a notice in “ Science Gossip” that on his South Ameiican Expedition he discovered evidences of glacial action on a scale so extensive as to more than suggest that the Southern Hemisphere has undergone a similar general glaciation to that of the Northern. The glaciation has been traced as far as the northern end of Chiloe Island. The Professor believes that during the glacial period the two hemispheres were capped with a sheet of ice of enormous thickness. Ancient moraines abound in South American valleys ; and in the Straits of Magellan one was found damming up a valley. But as I said before we must not overstate the action of glaciers. I see that Dr. Hector in his address last year, states that the mountain ice-cap performs its work, of eroding the elevated rock mass into ridges and peaks ; and that after the first rough excavation has been performed, axxd only the hard cox-es of crystalline or tough metamorphic rocks have survived the denudation, and when the valleys have all been perfectly moulded to perform their functions of ice gutters, then the process is admitted to be very slow. But to ascribe thus to glacier action the formation of the very ridges and peaks of mountain tops is, I think, unreasonable. In fact no larger amount of work can be assigned to glaciers even of the glacial epoch, as the Duke of Argyle remarks in a quotation made by Mr. Travel's, than that of deepening the valleys which existed before. That on the one hand when the period began it found the existing system of hills and valleys in the main determined, and on the other that it cannot have left them exactly as it found them. But this is very far from the view which Di - . Hector would seem to maintain—that mountain and valley with all their characteristic variety of surface have been cut out of the solid by enormous glacier’s. Now, the very opposite is the case. It is the pre-existing configuration of hill and valley and mountain range, which has determined the movement of these glaciers, so that, as the Duke of Argyle says, the effects of glacial denudation become a comparatively narrow question.

But whether we ascribe too much or too little to tho existence of a glacial epoch, let us for a moment consider what are the probable causes which might explain tho extraordinary changes of climate which have certainly existed in the earth in very distant epochs of time. There are two sources of heat which have varied greatly—the heat of the sun and heat from the body of the earth itself. Our faculties can form no conception, and can make no answer to the question, how far the forces which are in activity in tho sun have exhausted themselves. Say that such changes can bo worked out in any length of time that can bo assigned; such period, however vast, is nothing to eternity. To eternity no limit is assignable; priest and philosopher alike are ignorant here. But though wo can give no answer to the question, wo are assured that the forces which are in activity in the sun as revealed to us by light, “ the winged messenger," through tho spectroscope, are forces operating on the same substances as those which form the earth; that they must have had a beginning, as assuredly they will have an end; and that the sun will in the course of time cease to evolve heat, light, and electricity. It seems certain that they vary greatly in their intensity—at one epoch the heat of the sun may have been much greater than it is now, and at another far less. It is impossible they can have always been the same. I have dwelt longer on this subject than I should have done, had I not been desirous of introducing to your notice the very plausible theory of Mr. Croli—a theory rendered more interesting because Darwin has used it to explain facts in connexion with the distribution of plants and animals, and because it involves the admission that a glacial period existed in tho Southern Hemisphere, but at a period of about 13,000 years, or some multiple of that time, prior to the northern epoch. This, again, is in support of Captain Hutton’s views, who, with his usual caution, states that if he were to adopt the opinion that a glacial epoch once existed in the Southern Hemisphere, it would be with tho distinct understanding that it was far anterior to the pleistocene period—that is, anterior to the northern epoch. Dr. Knight then gives an epitome of Croll’s theory, and concludes his Address by shewing the probability that tho forces in activity in the Sun, were once in operation in the Globe wo inhabit.