of tons of coal, or about eight times the whole supply of coal supposed to exist in the earth.

Much light has been thrown on these three great problems of geology, viz., changes of climate, oscillations of sea-level, and the probable age of the earth, by the laborious researches of Mr. James Croll, of H. M. Geological Survey of Scotland, summarized in his carefully-prepared and able work on 'Climate and Time,' noted at the beginning of this paper. His theory of the secular change of climate is at once beautiful, simple, and complete. He does not claim that all submergences and emergences can be traced to those agencies which have produced changes of climate; but he does hold that many can, and, when taken in connection with the other wellunderstood causes, the subject is rendered far more intelligible. His theory affords, at least, some data for estimating geological time, the results of which entirely agree with those obtained by Sir William Thomon, Professor Tait, and others, by entirely different methods. He concurs in the view expressed by Herschel, that the varying eccentricity of the earth's orbit has not been sufficient in itself to materially affect climate; but he shows that, when taken in connection with the precession of the equinoxes, it may have done so indirectly, by bringing into operation physical agents amply sufficient to have produced, during one period, a mild, equable climate even in the polar regions, and, at another time, a con dition of glaciation extending far into what are now known as the temperate zones.

It is well known that the form of the earth's orbit is elliptical, and that the sun occupies one of the foci; that, while the mean distance of the earth from the sun is constant, the orbit, at times, becomes more elliptical, and again, as at present, more nearly approaches a circle. The superior limit of eccentricity is 0775, and the inferior limit 00314. The present limit is 0168; so that, assuming the earth's mean distance to be 91,400,000 miles (which is now shown to be slightly too little), her distance, when in perihelion, would be 89,864,480, and when in aphelion, 92,934,060, or a difference of 3,069,580. But, when eccentricity would be at its superior limit, the earth would be no less than 14,212,700 miles nearer the sun in the one position

than in the other. It is also well known that the line joining the solstices moves around the orbit backwards in about 25,000 years. This is called the precession of the equinoxes. Our winter in the northern hemisphere now occurs when the earth is in perihelion; but, it will be readily seen, in about 12,000 years our winter will occur when the earth is in aphelion, or furthest from the sun. If, at the same time, eccentricity should be at its superior limit, the earth would be 8,641,870 miles further from the sun than she is in winter at present. The heat received from the sun varies inversely as the square of the distance, and would, therefore, be one-fifth less during the six months of winter than now, and in summer, one fifth greater. It is true, winter would be thirty-six days longer than summer, and the less amount of heat received in winter would be exactly compensated by its greater length, as was shown by Herschel; so that the total amount of heat received between the two equinoxes would be the same, whatever might be the eccentricity of the orbit. Eccentricity cannot of itself, therefore, produce any very great changes of climate. But, while this is the case, Mr. Croll clearly shows that great eccentricity brings into operation a number of physical agents which do materially affect climate, and which are amply sufficient to produce a condition of glaciation in the hemisphere whose winter occurs in aphelion, and, at the same time, a perennial spring even in the polar regions of the other hemisphere whose winter occurs in perihelion, and, vice versa, during periods. of about 12,000 years each, till eccentricity becomes gradually lowered. He thus describes the effect that would be produced on the climate of the cold hemisphere : 'The reduction in the amount of heat received from the sun, owing to its increased distance, would lower the midwinter temperature to an enormous extent. In temperate regions the great portion of the moisture of the air is at present precipitated in the form of rain, and the very small proportion which falls as snow disappears in the course of a few weeks at most. But, in the circumstances under consideration, the mean winter temperature would be lowered so much below the freezing-point that what now falls as rain during that season would then fall as snow. This is not all;

the winters would then not only be colder than now, but they would also be much longer. . . . The lowering of the temperature and the lengthening of the winter would both tend to the same result, viz.: to increase the amount of snow accumulated during winter; for, other things being equal, the larger the snow-accumulating period the greater the accumulation. . . . As regards the absolute amount of heat received, increase of the sun's distance and lengthening of the winter are compensatory, but not so in regard to the amount of snow accumulated. The consequence of this state of things would be, that at the commencement of the short summer the ground would be covered with the winter's accumulation of snow. Again, the presence of so much snow would lower the summer temperature, and prevent, to a great extent, the melting of the snow.' This process would go on year after year, till the snow of winter would not be melted by the heat of the following summer. Exactly opposite effects would be produced in the other hemisphere, so that the general result would be that one hemisphere would be heated while the other would be cooled. This state of things would bring into play agencies which would cause the deflection of the great ocean currents, greatly intensifying the general results.

Mr. Croll discusses at great length the effects of ocean currents on climate. He shows that they are the great distributors of heat over the surface of the globe; that by carrying the heat from the equatorial regions to the polar they reduce the mean temperature of the former from 135° to 80°, and raise that of the latter from 83° below to zero. In other words, were it not for ocean currents the equator would be 55° warmer than at present, and the poles 83° colder, and the globe would be almost entirely uninhabitable. Any very great change, therefore, in the great equatorial ocean currents, so that their heat-distributing waters would be withdrawn from one hemisphere and spread out over the other, must have a wonderful influence on climate.

It is further shown that ocean currents are due to, and take the general direction of, the prevailing winds of the globe, and chiefly of the trades. The trade-winds are caused by the difference between the tem'perature of the equator and the poles. It

follows, therefore, under the circumstances which we have been considering, that the trades from the cold hemisphere would be much stronger than those from the warm. This would have the effect of withdrawing the equatorial ocean currents from the cold hemisphere and turning them into the warm, greatly intensifying the cold of the one and the heat of the other.

The nearness of the sun in perigee would have the effect of greatly increasing the accumulation of snow. This would result as follows: the currents of air from the warm to the cold regions would be greatly increased; and, evaporation being also increased, vast quantities of moisture would be transported to the cold parts, and would there be condensed and fall as snow. The heaviest fall of snow would, therefore, take place in summer; and, notwithstanding the nearness of the sun, he would have little melting power, because of the fogs which would be formed, and which would cut off his rays. These various agents would act on each other in such a way as to increase the general result; and we cannot wonder that the cold hemisphere would become, during long ages, capped with a sheet of ice thousands of feet in thickness, as was the case in the glacial epoch; while the other hemisphere would enjoy a mild, equable climate. As the solstitial points would gradually turn around, the contrary process would commence. The glaciated hemisphere would become warm, and the warm hemisphere cold, till the ice would be all melted from the one, and accumulated on the other.

It follows from this theory that the glacial epoch was not one continued duration of cold and ice, but must have consisted of a long succession of alternate cold and warm periods of about 12,000 years each, the warm periods of the one hemisphere corresponding with the cold periods of the other. There must have been a gradual increase of the two extremes of temperature till the greatest eccentricity was attained, and then a gradual decline till the normal condition of things was again reached. That there was this succession of cold and warm periods in the glacial epoch, there is considerable evidence; though, from the nature of the case, we know there would be, to a great extent, an obliteration of the evidences of former glacial periods,

and the indications of the last would be most clearly marked. We have, here, an explanation of the hitherto perplexing problem of the occurrence in the same beds of the post-tertiary period, of the remains of mollusca and maminalia of a tropical type with those of an extremely arctic character. Particularly in England is this the case. We find the lion, the tiger, the hyena, the elephant, and the rhinoceros associated with the ermine, the reindeer, and the muskOX. The one class lived during the warm period, and the other, during the closely following cold period.

Such epochs of alternate cold and warm periods must have often occurred during past time; as often as great eccentricity. The only evidences that we could reasonably expect these cold periods to have left us are transported boulders. These, however, are sufficient, as we know of no agency that could produce such a result but ice. Transported boulders are found in almost every age of geological time.

This theory affords a beautiful explanation of the coal formations; for we have, in the warm inter-glacial periods, the very condition of climate best suited to the growth of those kinds of trees and plants of which our coal is composed; as we have, also, in the following cold periods, a condition of things best suited to the preservation of those plants, and their conversion into coal. Wherever we find evidence of glaciation, we also find evidence of submergence of the land along with it. This is a suggestive fact. Let us see what bearing Mr. Croll's theory has on this point. The accumulation of an enormous ice-cap on one hemisphere, while the other would be free of ice, would have the direct effect of shifting the centre of gravity of the earth. If the ice-cap, say of the northern hemisphere, had a thickness equal in weight to 1,000 feet of rock, the centre of gravity would be shifted 500 feet north. The waters of the oceans adjust themselves with direct reference to the centre of gravity. They would, therefore, flow from the southern hemisphere, so that there would be an emergence of the land to the extent of 500 feet; and they would rise on the northern hemisphere to the same extent, wherever there were openings in the ice, and cause a submergence.

When the ice-cap would be transferred to the southern hemisphere, the

centre of gravity would be shifted 1,000 feet south, or 500 feet south of its mean position, which would cause a total oscillation of sea-level to the extent of about 1,000 feet. Again, the weight of the water thus pulled over from one heinisphere to the other, would tend to increase the general result. But the displacement of the centre of gravity must have been much greater than 500 feet on either side of its main position; for, during glaciation, the ice-cap must have been of enormous thickness. This will be more readily conceded from the following considerations. From calculations based on actual observations, the icesheet of the small continent of Greenland is supposed to attain a thickness in the interior of 10,000 feet. The southern hemisphere is known to be much colder at the present time than the northern, and the land surrounding the pole, of vast extent, about 28,000 miles in diameter. From reliable calculations, the antartic ice-cap is estimated to attain a thickness, at or near the pole, of at least six miles. During the glacial epoch, when the whole hemisphere was capped with ice down to at least the fiftieth parallel, the flow of the ice, which has left so many prodigious results, could only have been caused by the pressure of its great thickness, and could only take the general direction of the equator, being the direction of least resistance. How enormous, then, must have been the thickness in high latitudes of this vast continental glacier-so thick, that the White Mountains of New Hampshire were not a sufficient obstacle to impede its progress, or even to deflect it from its course! We have, here, a simple explanation of oscillations of sealevel, which must have occurred as often as glaciation. If coal be an inter-glacial formation, as is contended, we can readily understand how it was that coal pericds were always followed by submergence. This explanation, taken in connection with the other well understood causes of submergence, tends greatly to remove the mystery that has hitherto attached to the second great problem of geology.

If the intense cold which gives character to the glacial epoch, has been caused indirectly by great eccentricity of the earth's orbit, we have a means of ascertaining with tolerable accurancy the date of its commencement, and the length of its duration. ·

This gives at least one time-measure with which to approach the third problem discussed in this paper, viz., the probable age of the earth.

:

According to formulæ given by M. Leverrier, Mr. Croll has made calculations extending over three millions of years past. He finds that eccentricity attained very high values during three distinct periods of that time the first, about 2,500,000 years back; the second, 850,000 years ago; and the third, about 200,000 years ago. The first and second periods lasted for about 200,000 years each; and the third, for 160,000, from 240,000 years ago to about 80,000 years ago. For sufficient reasons the glacial epoch is assigned to the last period, and the middle of the Miocene and Eocene ages, to the other two respectively. The glacial epoch, therefore, lasted for about 160,000 years, during which time the

climate of each hemisphere was alternately warm and cold for periods of about 12,000 years each. Sir Charles Lyell dated the glacial epoch at 1,000,000 years back. If, then, Mr. Croll's theory be correct, and it is being rapidly accepted by those best able. to judge, Lyell's estimate must be reduced by four-fifths of its amount. If we reduce his entire estimate in the same proportion, we have 48,000,000 of years, instead of 240,000,000, as the age of the earliest fossiliferous rocks. Even this reduced amount is, in all probability, vastly too great. Having obtained, however, with tolerable accuracy, the date of the last great geological epoch, and, it may be also, of the Miocene and Eocene.periods, we may venture the hope, that science will yet discover, within reasonable limits, the probable age of the earth. S. H. JANES.

turned to Canada early this summer, at Niagara, and have since travelled through it from west to east. I have crossed the broad fertile plains of Ontario, lived among the quaint old-fashioned homesteads of Quebec, roamed the pleasant valleys and skirted the rugged iron-bound shores of Acadia; and during my progress, I have been naturally led to speculate on the future condition of the country and the destiny of its people. I have travelled slowly, making Toronto, Montreal, Quebec, St John, and Halifax, my headquarters at various times. I have taken advantage of my opportunities to visit all the surrounding places of interest, and to mix among and endeavour to gain a thorough knowledge of the social and political condition. of the people; and I consider that I have been amply rewarded for my trouble, in noting the immense progress that has been made in wealth and in political unity during the last decade.

These provinces ten years since were disunited, knowing little of each other, and having no sympathies or interests in common. Suffering from the revolution in commerce caused by the abrogation of the Reciprocity Treaty, many turned their eyes longingly across the border, sighing, for annexation, and showing little faith in the success of the scheme of union which was then about to be tested.

How different do we find it to-day? The country united, and proud of its unity; its people showing a confidence in their future, recovered from the blow that American spleen dealt her commerce, and determined in the future not to allow themselves to be made the sport of their cousins across the border. Yes! the scattered provinces of ten years ago, to-day form the nucleus of a mighty nation; their people looking forward to the day, in the not far-distant future, when they will be called upon to take their stand among the nations

of the earth, and proud to be called Canadians.

The progress of this spirit must be much more evident to one who has been so long absent from the country, than to those who have remained at home; but it must, I think, have made itself apparent to every thinking man. As I before remarked, I have endeavoured to make myself acquainted with the sympathies and aspirations of the people, by passing my days amongst them, and entering with them into the ordinary intercourse of every-day life; and I have found that, in all the different provinces, especially among the young men (who must rule this country in a few years), there is a widespread feeling in favor of independence. To give you an idea of the people I have met, I cannot do better than relate a little incident that happened in Montreal.

One beautiful day, last August, I had wended my way to the mountain, and taking advantage of the cool shade of the trees, I lay idly smoking a cigar. The city was spread at my feet, the towers of Notre Dame rising like sentinels above it, while the royal St. Lawrence stretched away like a silvery serpent, as far as the eye could reach.

It was on such a day and under such circumstances, when my thoughts were as far from politics as heaven is from hades, that I was disturbed by a young man of perhaps twenty-five or thirty summers, who wandered through the woods, and apparently without seeing me, threw himself down on a little hillock, close beside me, and gazing at the beautiful prospect spread before us, was soon lost in thought. I ventured to disturb him, and after a few remarks on surrounding objects, we insensibly glided into a discussion on the state of the country, and as he seemed to be intelligent and well-read, I asked him to give me his idea of the present state of things, and what he thought of the political future.

have too many politicians and too few statesmen.'

I interrupted him to ask him to favor me with his definition of politicians and states

men.

A politician,' he replied, 'is one who will take advantage of any differences of creed, sect, and nationality; who will inflame the prejudices of the people, and carry partisan feelings to any extreme, to further his own selfish ends, or to benefit his party. A statesman, on the contrary, is one who will strive to harmonize all differences between the different classes, for the interest of the state. The policy of the one is expediency, and he looks for an immediate reward in the shape of the spoils of office; the policy of the other patriotism, and he is satisfied with the gratitude of generations yet unborn.'

'But,' I said, it must be evident to you that it is a task of infinite magnitude to unite under one nationality, elements so discordant as the French Catholics of Quebec and the English and Scotch Protestants of Ontario, who are not only of different blood, but what is often of more consequence, are each violently prejudiced against the religion of the other.'

And why is it so?' he exclaimed; 'they are all Canadians, and but for the intrigues of petty politicians would be thoroughly united at the present day. The cause which I have at heart,' he continued warmly, 'is one too sacred and too delicate for the vulgar politician; it is one which requires the master hand of a statesman. The cause is ripening, but it needs an apostle; the people are preparing, but we want the Man.' I told him that I thought his ideas were very far advanced, and that while I might merely be inclined to consider him an enthusiast, others would perhaps think him. disloyal.

'I am no farther advanced,' he replied, 'than thousands of my fellow-countrymen ; and,' he added proudly, I think our first loyalty is due to ourselves. It is very well to talk of loyalty to a country three thousand miles away, to which we are only bound by traditional ties, and towards whom almost one half of our people have no ties, even of blood; but we must consider what is best for our own country, and not be influenced by any sentimer.tal ideas of loyalty towards England. Our task may