 section 21 of Science in Short Chapters. Let us now consider the third danger that of darkness. The seriousness of this may be inferred from the following description of the journey of the Nassau Balloon, published at the time. It seemed to the aeronauts as if they were cleaving their way through an interminable mass of black marble, in which they were embedded, and which solid a few inches before them seemed to soften as they approached in order to admit them still further within its cold and dusky enclosure. In this way they proceeded blindly, as it may well be called, until about 3.30 a.m., when in the midst of the impenetrable darkness and profound stillness an unusual explosion issued from the machine above, followed by a violent rustling of the silk, and all the signs which might be supposed to accompany the bursting of the balloon. The car was violently shaken. A second and a third explosion followed in quick succession. The danger seemed immediate when suddenly the balloon recovered her usual form and stillness. These alarming symptoms seemed to have been produced by collapsing of the balloon under the diminished temperature of the upper regions after sunset, and the silk forming into folds under the netting. Now when the guide-rope informed the voyagers that the balloon was too near the earth, ballast was thrown out, and the balloon rising rapidly into a thinner air experienced a diminution of pressure and consequent expansion of the gas. The cold during the night ranged from a few degrees below to the freezing point. As morning advanced the rushing of waters was heard, and so little were the aeronauts aware of the course which they had been pursuing during the night that they supposed themselves to have been thrown back upon the shores of the German ocean or about to enter the Baltic, whereas they were actually over the Rhine, not far from Koblenz. All this blind drifting for hours, during which the balloon may be carried out to sea, and opportunities of safe descent may be lost, is averted in an arctic balloon voyage which would be made in the summer when the sun never sets. There need be no break in the survey of the ground passed over, no difficulty in pricking upon a chart the course taken and the present position at any moment. With an horizon of fifty to one hundred miles radius the approach of such danger as drifting to the open ocean would be perceived in ample time for descent and, as a glance at the map will show, this danger cannot occur until reaching the latitudes of inhabited regions. The arctic aeronauts will have another great advantage over those who ascend from any part of England. They can freely avail themselves of Mr. Green's simple but most important practical invention, the drag rope. This is a long and rather heavy rope trailing on the ground. It performs two important functions. First, it checks the progress of the balloon causing it to move less rapidly than the air in which it is immersed. The aeronaut thus gets a slight breeze equivalent to the difference between the velocity of the wind and that of the balloon's progress. He may use this as a fulcrum to affect a modicum of steerage. The second and still more important use of the drag rope is the very great economy of ballast it achieves. Suppose the rope to be one thousand feet long, its weight equal to one pound for every ten feet, and the balloon to have an ascending power of fifty pounds. It is evident that under these conditions the balloon will retain a constant elevation of five hundred feet above the ground below it, and that five hundred feet of rope will trail upon the ground. Thus, if a mountain is reached, no ballast need be thrown away in order to clear the summit, as the balloon will always lift its five hundred feet of rope, and thus always rise with the upslope and descend with the downslope of the hill and dale. The full use of this simple and valuable adjunct to aerial travelling is prevented in such a country as ours by the damage it might do below, and the temptation it affords to mischievous idiots near whom it may pass. In the course of many conversations with various people on this subject I have been surprised at the number of educated men and women who have anticipated with something like a shudder the terrible cold to which the poor aeronauts will be exposed. This popular delusion which pictures the Arctic regions as the abode of perpetual freezing is so prevalent and general that some explanation is demanded. The special characteristic of Arctic climate is a cold and long winter and a short and hot summer. The winter is intensely cold simply because the sun never rises, and the summer is very hot because the sun is always above the horizon, and unless hidden by clouds or mist is continually shining. The summer heat of Siberia is intense, and the vegetable proportionately luxuriant. I have walked over a few thousand miles in the sunny south, but never was more oppressed with the heat than in walking up the Tromsdahl to visit an encampment of Laplanders in the summer of 1856. On the 17th July I noted the temperature on board the steam packet where we were about three degrees north of the Arctic Circle. It stood at 77 degrees, well shaded in a saloon under the deck. It was 92 degrees in the Rok Lugar, a little smoking saloon built on deck, and 108 degrees in the sun on deck. This was out at sea, where the heat was less oppressive than on shore. The summers of Arctic Norway are very variable on account of the occasional prevalence of misty weather. The balloon would be above much of the mist, and would probably enjoy a more equitable temperature during the twenty-four hours than in any part of the world where the sun sets at night. I am aware that the above is not in accordance with the experience of the Arctic explorers, who have summered in such places as Smith's Sound. I am now about to perpetrate something like a heresy, by maintaining that the summer climate there experienced by these explorers is quite exceptional, is not due to the latitude, but to causes that have hitherto escaped the notice of the explorers themselves and of physical geographers generally. The following explanation will probably render my view of this subject intelligible. As already stated, the barrier fringe that has stopped the progress of Arctic explorers is a broken mountainous shore, down which is pouring a multitude of glaciers into the sea. The ice of these glaciers is, of course, fresh water ice. Now we know that when ice is mixed with salt water we obtain what is called a freezing mixture, a reduction of temperature far below the freezing point, due to the absorption of heat by the liquefaction of the ice, thus the heat of the continuously shining summer sun at this particular part of the Arctic region is continuously absorbed by this powerful action, and a severity quite exceptional is thereby produced. Every observant tourist who has crossed an alpine glacier on a hot summer day has felt the sudden change of climate that he encounters on stepping from terra firma on to the ice, and in which he remains immersed as long as he is on the glacier. How much greater must be this depression of temperature, where the glacier ice is broken up and is floating in seawater, to produce a vast area of freezing mixture which would speedily bring the hottest blasts from the Sahara down to many degrees below the freezing point. A similar cause retards the beginning of summer in Arctic Norway and in Finland and in Siberia. So long as the winter snow remains unmelted, i.e., till about the middle or end of June, the air is kept cold, all the solar heat being expended in the work of thawing. This work finished, then the warming power of a non-setting sun becomes evident, and the continuously accumulating heat of his rays displays its remarkable effect on vegetable life and everything capable of being warmed. These peculiarities of Arctic climate must become exaggerated as the pole is approached, the winter cold still more intense, and the accumulation of summer heat still greater. In the neighbourhood of the North Cape, where these contrasts astonish English visitors, where inland summer travelling becomes intolerable on account of the clouds of mosquitoes, the continuous sunshine only lasts from May 11 to August 1. At the North Pole, the sun would visibly remain above the horizon during about 7 months from the first week in March to the first week in October. This includes the effect of refraction and the prolonged summer of the Northern Hemisphere due to the eccentricity of the Earth's orbit. This continuance of sunshine, in spite of the moderate altitude of the solar orb, may produce a very genial summer climate at the pole. I say May, because mere latitude is only one of the elements of climate, especially in high latitudes. Very much depends upon surface configuration and the distribution of land and water. The region in which our Arctic expedition ships have been ice-bound combines all the most unfavourable conditions of Arctic summer climate. It is extremely improbable that those conditions are maintained all the way to the pole. We know the configuration of Arctic Europe and Arctic Asia that they are masses of land spreading out northward round the Arctic Circle and narrowing southward to angular terminations. The southward configuration and northward outspreading of North America are the same, but we cannot follow the northern portion to its boundary as we may that of Europe and Asia, both of which terminate in an Arctic Ocean. Greenland is remarkably like Scandinavia. Davis's Strait, Baffins Bay, and Smith's Sound corresponding with the Baltic and the Gulf of Bothnia. The deep fjords of Greenland, like those of Scandinavia, are on its western side, and the present condition of Greenland corresponds to that of Norway during the milder period of the last glacial epoch. If the analogy is maintained a little further north than our explorers have yet reached, we must come upon a polar sea just as we came upon the white sea and the open Arctic Ocean if we simply travel between 400 and 500 miles due north from the head of the frozen Gulf of Bothnia. Such a sea, if unencumbered with land ice, will supply the most favourable conditions for a genial Arctic summer, especially if it be dotted with islands of moderate elevation, which the analogies of the known surroundings render so very probable. Such islands may be inhabited by people who cannot reach us on account of the barrier wall that has hitherto prevented us from discovering them. Some have even supposed that a Norwegian colony is there imprisoned. Certainly the early colonists of Greenland have disappeared, and their disappearance remains unexplained. They may have wandered northwards, mingled with the Eskimo, and have left descendants in this unknown world. If any of Franklin's crew crawled far enough, they may still be with them, unable to return. In reference to these possibilities, it should be noted that a barrier fringe of mountainous land, like that of Greenland and Arctic America, would act as a condensing ground upon the warm air flowing from the south, and would there accumulate the heavy snows and consequent glaciers, just as our western hills take so much of the rain from the vapor-laden winds of the Atlantic. The snowfall immediately round the pole would thus be moderated, and the summer begin so much earlier. I have already referred to the physical resemblances of Baffins Bay, Smith's Sound, etc., to the Baltic, the Gulf of Bothnia, and Gulf of Finland. These are frozen every winter, but the Arctic Ocean, due north of them, is open all the winter and every winter. The hardy Norse fishermen are gathering their chief harvest of codfish in the open sea around and beyond the North Cape, Nordkin, etc., at the very time when the Russian fleet is hopelessly frozen up in the Gulf of Finland. But how far do north of this frozen Baltic are these open sea fishing banks, more than 14 degrees, more than double the distance that lies between the winter quarters of some of our ships in Smith's Sound and the pole itself? This proves how greatly physical configuration and oceanic communication may oppose the climatic influences of mere latitude. If the analogy between Baffins Bay and the Baltic is complete, a polar sea will be found that is open in the summer at least. On the other hand, it may be that ranges of mountains covered with perpetual snow and valleys piled up with huge glacial accumulations extend all the way to the pole, and thus give to our globe an Arctic ice cap like that is displayed on the planet Mars. This however is very improbable, for if it were the case we ought to find a circumpolar ice wall like that of the Antarctic regions, the Arctic ocean beyond the North Cape should be crowded with icebergs, instead of being open and iceless all the year round. With such a configuration the ice wall should reach Spitzbergen and stretch across to Nova Zembla, but instead of this we have there such an open stretch of Arctic water, that in the summer of 1876 Captain Kjelsen of Tromsø sailed in a whaler to latitude 81 degrees thirty minutes without sighting ice. He was then but 510 geographical miles from the pole, with open sea right away to his north horizon, and nobody can say how much farther. These problems may all be solved by the proposed expedition. The men are ready and willing. One volunteer has even promised one thousand pounds, unconditioned, that he shall be allowed to have a seat in one of the balloons. All that is wanted are the necessary funds, and the amount required is but a small fraction of what is annually expended at our race courses upon villainous concoctions of carbonic acid and methylated cider, bearing the name of champagne. Arrangements are being made to start next May, but in the meantime many preliminary experiments are required. One of these, concerning which I have been boring Commander Chane and the committee, is a thorough and practical trial of the staying properties of hydrogen gas when confined in given silken or other fabrics saturated with given varnishes. We are still ignorant on this fundamental point. We know something about coal gas, but little or nothing of the hydrogen, such as may be used in the foregoing expedition. Its exmosis, as proven by Graham, depends upon its adhesion to the surface of the substance confining it. Every gas has its own specialty in this respect, and a membrane that confines a hydrocarbon like coal gas may be very unsuitable for pure hydrogen, or vice versa. Hydrogen passes through hard steel, carbonic oxide through red hot iron plates, and so on with other gases. They are guilty of most improbable proceedings in the matter of penetrating apparently in penetrable substances. The safety of the aeronauts and the success of the aerial exploration primarily depends upon the length of time that the balloons can be kept afloat in the air. A sort of humanitarian cry has been raised against this expedition on the ground that unnaturally good people, of whom we now meet so many, should not be guilty of aiding and abetting a scheme that may cause the sacrifice of human life. These kind friends may be assured that in spite of their scruples the attempt will be made by men who share none of their fears, unless the preliminary experiments prove that a balloon cannot be kept up long enough. Therefore the best way to save their lives is to subscribe at once for the preliminary expense of making these trials, which will either discover means of travelling safely or demonstrate the impossibility of such ballooning altogether. Such experiments will have considerable scientific value in themselves and may solve other problems besides those of Arctic exploration. Why not apply balloons to African exploration or the crossing of Australia? The only reply to this is that we know too little of the practical possibilities of such a method of travelling when thus applied. Hitherto the balloon has only been a sensational toy. We know well enough that it cannot be steered in a predetermined line, i.e. from one point to another point, but this is quite a different problem from sailing over a given surface of considerable area. This can be done to a certain extent, but we want to know definitely to what extent and what are the limits of reliability and safety. With this knowledge, and its application by the brave and skilful men who are so eager to start, the solution of the polar mystery assumes a new and far more hopeful phase than it has ever before presented. The Anglo-American Arctic Expedition Commander Chain has gone to America to seek the modest equipment that his own countrymen are unable to supply. He proposes now that his expedition shall be Anglo-American. I have been asked to join an Arctic Council to cooperate on this side and have refused on anti-patriotic grounds. As a member of the former Arctic Committee, I was so much disgusted with the parsimony of our millionaires and the anti-geographical conduct of the Seville Row Mutual Admiration Society, that I heartily wish that in this matter our American grandchildren may lick the Britishers quite complete. It will do us much good. My views expressed in the Gentleman's Magazine of July 1880 and repeated above remain unchanged, except in the direction of confirmation and development. I still believe that an enthusiastic, practically trained, sturdy Arctic veteran who has endured hardship both at home and abroad, who's craving eagerness to reach the pole amounts to a positive monomania, who lives for this object alone, and is ready to die for it, who will work at it purely for the work's sake, will be the right man, in the right place when at the head of a modestly but efficiently equipped polar expedition, especially if Lieutenant Schwatka is his second in command. They will not require luxurious saloons nor many cases of champagne. They will care but little for amateur theatricals. They will follow the naval traditions of the old British sea dogs, rather than those of our modern naval lap dogs, and will not turn back after a first struggle with the cruel Arctic ice, even though they should suppose it to be paleo-christic. scientific aerostation has lost its most promising expert by the untimely death of Walter Powell. He was not a mere sensational ballooner, nor one of those dreamers who imagine they can invent flying machines, or steer balloons against the wind by mysterious electrical devices or by mechanical paddles, fan wheels, or rudders. He perfectly understood that a balloon is at the mercy of atmospheric currents, and must drift with them. But nevertheless he regarded it as a most promising instrument for geographical research. I had a long conference with him on the subject in August last, when he told me that the main objects of the ascents he had already made, and should be making for some little time forward, were the acquisition of practical skill, and of further knowledge of atmospheric currents, after which he should make a dash at the Atlantic, with the intent of crossing to America. On my part I repeated with further argument what I have already urged on page 113 of the Gentleman's Magazine for July 1880, namely the primary necessity of systematic experimental investigation of the rate of exosmosis oozing out of the gas from balloons made of different materials and variously varnished. Professor Graham demonstrated that this molecular permeation of gases and liquids through membranes mechanically airtight depends upon the adhesion affinities of particular solids for other particular fluids, and these affinities vary immensely, their variations depending on chemical differences rather than upon mechanical impermeability. My project to attach captive balloons of small size to the roof of the polytechnic institution, holding them by a steel yard that should indicate the pull due to their ascending power, and the rate of its decline according to the composition of the membrane, was heartily approved by Mr. Powell, and, had the polytechnic survived, would have been carried out, as it would have served the double purpose of scientific investigation and of sensational advertisement for the outside public. If the aeronaut were quite clear on this point, could calculate accurately how long his balloon would float, he might venture with deliberate calculation on journeys that without such knowledge are mere exploits of blind daring. The varnishes at present used are all permeable by hydrogen gas and hydrocarbon coal gas, as might be expected a priori from the fact that they are themselves solid hydrocarbons, soluble in other liquid or gaseous hydrocarbons. Nothing, as far as I can learn, has yet been done with silistic or boracic varnishes, which are theoretically impermeable by hydrogen and its carbon compounds. But whether they are practically so under ballooning conditions, and can be made sufficiently pliable and continuous, are questions only to be solved by practical experiments of the kind above named. Now, that the best man for making these experiments is gone, somebody else should undertake them. Unfortunately, they must of necessity be rather expensive. Estimating the actual consumption of coal for home use in Great Britain at 110 millions of tonnes per annum, a rise of eight shillings per tonne to consumers is equivalent to a tax of 44 millions per annum. These are the figures taken by Sir William Armstrong in his address at Newcastle last February. As the recent abnormal rise in the value of coal has amounted to more than this, consumers have been paying at some periods above a million per week as premium on fuel, even after making fair deduction for the rise of price necessarily due to the diminishing value of gold. Are we the consumers of coal to write off all of this as a dead loss, or have we gained any immediate or prospective advantage that may be deducted from the bad side of the account? I suspect that we shall gain sufficient to ultimately balance the loss and, even after that, to leave something on the profit side. The abundance of our fuel has engendered a shameful wastefulness that is curiously blind and inconsistent. As a typical example of this inconsistency, I may mention a characteristic incident. A party of young people were sitting at supper in the house of a colliery manager. Among them was the vicar of the parish, a very jovial and genial man, but most earnest with all in his vocation. Jokes and banterings were freely flung across the table, and no one enjoyed the fun more heartily than the vicar. But presently one unwary youth threw a fragment of breadcrust at his opposite neighbour and thus provoked retaliation. The countenance of the vicar suddenly changed, and in stern clerical tones he rebuked the wickedness of thus wasting the bounties of the Almighty. A general silence followed, and a general sense of guilt prevailed among the revelers. At the same time, and in the same room, a blazing fire in an ill-constructed open fireplace was glaring reproachfully at all the guests, but no one heeded the immeasurably greater and utterly irreparable waste that was there proceeding. To every unit of heat that was fully utilised in warming the room, there were eight or nine passing up the chimney to waste their energies upon the senseless clouds and boundless outer atmosphere. A large proportion of the vicar's parishioners are colliers, in whose cottages huge fires blaze most wastefully all day and are left to burn all night to save the trouble of relighting. The vicar diligently visits these cottages and freely admonishes where he deems it necessary, yet he sees in this general waste of coal no corresponding sinfulness to that of wasting bread. Why is he so blind in one direction, while his moral vision is so microscopic in the other? Why are nearly all Englishmen and Englishwomen as inconsistent as the vicar in this respect? There are doubtless several combining reasons for this, but I suspect that the principal one is the profound impression which we have inherited from the experience and traditions of the horrors of bread famine. A score of proverbs express the important practical truth that we rarely appreciate any of our customary blessings until we have tasted the misery of losing them. Englishmen have tasted the consequences of approximate exhaustion of the national grain store, but have never been near to the exhaustion of the national supply of coal. I therefore maintain most seriously that we need a severe coal famine, and if all the colliers of the United Kingdom were to combine for a simultaneous winter strike of about three or six months duration, they might justly be regarded as unconscious patriotic martyrs, like soldiers slain upon a battlefield. The evils of such a thorough famine would be very sharp, and proportionally beneficent, but only temporary. There would not be time enough for manufacturing rivals to sink pits and at once erect competing ironworks, but the whole world would partake of our calamity, and the attention of all mankind would be aroused to the sinfulness of wasting coal. Six months of compulsory wood and peat fuel, with total stoppage of iron supplies, would convince the people of these islands that waste of coal is even more sinful than waste of bread. Would lead us to reflect on the fact that our stock of coal is a definite and limited quantity that was placed in the present storehouse long before human beings came upon the earth. That every ton of coal that is wasted is lost forever, and cannot be replaced by any human effort, while bread is a product of human industry, and its waste may be replaced by additional human labor. That the sin of bread wasting does admit of agricultural atonement, while there is no form of practical repentance that can positively and directly replace a hundred weight of wasted coal. Being short of the practical and impressive lesson of bitter want is likely to drive from our households that wretched fetish of British adoration the open Englishman's fireside. Reason seems powerless against the superstition of this form of fire worship. Tell one of the idolaters that his household God is wasteful and extravagant, that five sixth of the heat from his coal goes up the chimney, and he replies, I don't care if it does, I can afford to pay for it, I like to see the fire, and have the right to waste what is my own. Tell him that healthful ventilation is impossible, while the lower part of a room opens widely into a heated shaft, that forces currents of cold air through doors and window leakages, which unite to form a perpetual chill-brained stratum on the floor, and leaves all above the mantelpiece comparatively stagnant. Tell him that no such thing as draughts should exist in a properly warmed and ventilated house, and that even with a thermometer at zero outside every part of a well-ordered apartment should be equally habitable, instead of merely a semi-circle around the hearth of the fire worshiper. He shuts his ears, locks up his understanding, because his grandfather and grandmother believed that the open-mouthed chimney was the one and only true English means of ventilation. But suppose we were to say, you love a cheerful blaze, can afford to pay for it, and therefore care not how much coal you waste in obtaining it. We also love a cheerful blaze, but we have a greater version to coal-smoke and tarry vapours, and we find that we can make a beautiful fire, quite inoffensive even in the middle of the room, provided we feed it with stale, quatern loaves. We know that such fuel is expensive, but can afford to pay for it, and choose to do so. Would not he be shocked at the sight of the blazing loaves if this extravagance were carried out? This popular inconsistency of disregarding the waste of a valuable and necessary commodity of which the supply is limited and un-renewable, while we have such proper horror of willfully wasting another similar commodity which can be annually replaced as long as man remains in living contact with the earth, will gradually pass away when rational attention is directed to the subject. If the recent very mild suggestion of a coal famine does something towards placing coal on a similar pedestal of popular veneration to that which is held by the staff of life, the million a week that it has cost the coal consumer will have been profitably invested. Many who were formerly deft to the exhortations of fuel economists are now beginning to listen. Forty shillings per tonne has acted like an incantation upon the spirit of Count Rumpford. After an oblivion of more than eighty years, his practical lessons have again sprung up among us. Some are already inquiring how he managed to roast one hundred twelve pounds of beef at the Foundling Hospital with twenty-two pounds of coal, and to use the residual heat for cooking the potatoes, and why it is that with all our boasted progress we do not now in the latter third of the nineteenth century repeat that which he did in the eighteenth. The fact that the consumption of coal in London during the first four months of 1873 has in spite of increasing populations amounted to forty-nine thousand seven hundred seven tons less than the corresponding period of 1872 shows that some feeble attempts have been made to economize the domestic consumption of fuel. One very useful result of the recent scarcity of coal has been the awakening of a considerable amount of general interest in the work of stock taking, a tedious process which improvident people are too apt to shirk, but which is quite indispensable to sound business proceedings either of individuals or nations. There are many discrepancies in the estimates that have been made of the total available quantity of British coal. The speculative nature of some of the data renders this inevitable, but all authorities appear to agree on one point vis that the amount of our supplies will not be determined by the actual total quantity of coal under our feet, but by the possibilities of reaching it. This is doubtless correct, but how will these possibilities be limited, and what is the extent or range of the limit? On both these points I ventured to disagree with the eminent men who have so ably discussed this question. First, as regards the nature of the limit or barrier that will stop our further progress in coal getting, this is generally stated to be the depth of the seams. The Royal Commissioners of 1870 based their tables of the quantity of available coal in the visible and concealed coal fields upon the assumption that four thousand feet is the limit of possible working. This limit is the same that was taken by Mr. Hull ten years earlier. Mr. Hull, in the last edition of The Coal Fields of Great Britain, page 326, referring to Professor Ramsey's estimate, says these estimates are drawn up for depths down to four thousand feet below the surface, and even beyond this limit, but with this latter quantity it is scarcely necessary that we should concern ourselves. I shall presently show reasons for believing that the time may ultimately arrive when we shall concern ourselves with this deep coal and actually get it, while on the other hand that remote epoch will be preceded by another period of practical approximate exhaustion of British coal supply, which is likely to arrive long before we reach a working depth of four thousand feet. The Royal Commissioners estimate that within the limits of four thousand feet we have hundreds of square miles of attainable coal capable of yielding, after deducting forty percent for loss in getting, etc., one hundred forty six million four hundred eighty millions of tons, or if we take this with Mr. Hull's deduction of one twentieth for seams under two feet in thickness, there remains one hundred thirty nine thousand millions of tons, which at present rate of consumption would last about twelve hundred years. But the rate of consumption is annually increasing, not merely on account of increasing population, but also from the fact that mechanical inventions are perpetually superseding hand labour, and the source of power in such cases is usually derived from coal. This consideration induced Professor Jevons in eighteen sixty-five to estimate that between eighteen sixty-one and eighteen seventy-one, the consumption would increase from eighty-three million five hundred thousand tons to one hundred eighteen million tons. Mr. Hunt's official return for eighteen seventy-one shows that this estimate was a close approximation to the truth, the actual total for eighteen seventy-one having been one hundred seventeen million three hundred fifty-two thousand and twenty-eight tons. At this rate of an arithmetical increase of three and a half tons per annum, one hundred thirty-nine thousand millions of tons would last but two hundred fifty years. Mr. Hull, taking the actual increase at three millions of tons per annum, extends it to two hundred seventy-six years. Hitherto the annual increase has followed a geometrical rather than arithmetical progress, and those who anticipate a continuance of this allow us a much shorter lease of our coal treasures. Mr. Price-Williams maintains that the increase will proceed in a diminishing ratio like that of the increase of population, and upon this basis he has calculated that the annual consumption will amount to two hundred seventy-four millions of tons a hundred years hence, and the whole available stock of coal will last about three hundred sixty years. The latest returns show for eighteen seventy-two an output of one hundred twenty-three million five hundred forty-six thousand seven hundred fifty-eight tons, which, compared with eighteen seventy-one, gives a rate of increase of more than double the estimate of Mr. Hull, and indicate that prices have not yet risen sufficiently to check the geometrical rate of increase. Mr. Hull very justly points out the emission in those estimates which do not take into account the diminishing ratio at which coal must be consumed when it becomes scarcer and more expensive. But on the other hand he omits the opposite influence of increasing prices on production, which has been strikingly illustrated by the extraordinary number of new coal mining enterprises that have been launched during the last six months. If we continue as we are now proceeding, a practical and permanent coal famine will be upon us within the lifetime of many of the present generation. By such a famine I do not mean an actual exhaustion of our coal seams, which will never be affected, but such a scarcity and rise of prices as shall annihilate the most voracious of our coal-consuming industries, those which depend upon abundance of cheap coal such as the manufacture of pig-iron, etc. The action of increasing prices has been but lightly considered hitherto, though its importance is paramount in determining the limits of our coal supply. I even venture so far as to affirm that it is not the depth of the coal seams, not the increasing temperature nor pressure, as we proceed downwards, nor even thinness of seam, that will practically determine the limits of British coal-getting, but simply the price per ton at the pit's mouth. In proof of this I may appeal to actual practice. Mr. Hull and others have estimated the working limit of thinness at two feet and agree in regarding thinner seams than this as unworkable. This is unquestionably correct so long as the getting is affected in the usual manner. A collier cannot lie down and hew a much thinner seam than this, if he works as colliers work at present. But the lead and copper miners succeed in working far thinner loads, even down to the thickness of a few inches, and the gold digger crushes the hardest component of the earth's crust to obtain barely visible grains of the precious metal. This extension of effort is entirely determined by market value at a sufficiently high price, the two feet limit of coal getting would vanish, and the collier would work after the manner of the lead miner. We may safely apply the same reasoning to the limits of depth. The four thousand feet limit of the Royal Commissioners is at present unattainable simply because the immediate prospective price of coal would not cover the cost of such deep sinking and working, but as prices go up pits will go down deeper and deeper still. The obstacles which are assumed to determine the four thousand feet limit are increasing density due to greater pressure and the elevation of temperature which proceeds as we go downwards. The first of these difficulties has I suspect been very much overstated, if not altogether misunderstood, though it is but fair to add that Mr. Hull, who most prominently dwells upon it, does so with all just and philosophic caution. He says that it is impossible to speak with certainty of the effect of the accumulative weight of three thousand or four thousand feet of strata on mining operations. In all probability one effect would be to increase the density of the coal itself and of its accompanying strata so as to increase the difficulty of excavating, and he concludes by stating that, in the face of these two obstacles, temperature and pressure ever increasing with the depth, I have considered it utopian to include in calculations having reference to coal supply any quantity, however considerable, which lies at a greater depth than four thousand feet. Beyond that depth I do not believe that it will be found practical to penetrate. Temperature rises up and presents insurmountable barriers. On one point I differ entirely from Mr. Hull, namely the conclusion that the increased density of the coal itself and of its accompanying strata will offer any serious obstacle. On the contrary there is good reason to believe that such density is one of the essential conditions for working deep coal. And at present depths of working density and hardness of the accompanying strata is one of the most important aids to easy and cheap coal getting. With a dense roof and floor the collier works vigorously and fearlessly and he escapes the serious cost of timbering. Those who have never been underground and only read of colliery disasters commonly regard the fire-damp and choke-damp as the collier's most deadly enemies, but the collier himself has quite as much dread of a rotten roof as either of these. He knows by sad experience how much bruising and maiming and crushing of human limbs are due to the friability of the rock above his head. Mr. Hull quotes the case of the Duncanfield colliery where at a depth of about twenty-five hundred feet the pressure is so resistless as to crush in circular arches of brick four feet thick and to snap a cast-iron pillar in twain, but he does not give any account of the density of the accompanying strata at the place of these occurrences. I suspect that it was simply a want of density that allowed the super-incumbent pressure to do such mischief. The circular arches of brick four feet thick were but poor substitutes for a roof of solid rock of forty or four hundred feet in thickness. An arch cut in such rock would be all keystone, and I may safely venture to affirm that if in the deep sinkings of the future we do encounter the increased density which Mr. Hull anticipates, this will be altogether advantageous. I fear, however, that it will not be so, that the chief difficulty of deep coal mining will arise from occasional running in due to deficient density, and that this difficulty will occur in about the same proportion of cases as at present, but will operate more seriously at the greater depths. A very interesting subject for investigation is hereby suggested. Do rocks of given composition and formation increase in density as they dip downwards, and if so, does this increase of density follow any law by which we may determine whether their power of resisting super-incumbent pressure increases in any approach to the ratio of the increasing pressure to which they are naturally subjected? If the increasing density and power of resistance reaches or exceeds this ratio, deep mining has nothing to fear from pressure. If they fall short of it, the difficulties arising from pressure may be serious. Fryability, viscosity, and power of resisting a crushing strain must be considered in reference to this question. Mr. Hull has collected a considerable amount of data bearing upon the rate of increase of temperature with depth. His conclusions give a greater rate of increase than is generally stated by geologists, but for the present argument I will accept without prejudice, as the lawyers say his basis of a range of one degree Fahrenheit for sixty feet. According to this the rocks will reach ninety-nine point six degrees, a little above blood heat at three thousand feet, and one hundred sixteen point three degrees at the supposed limit of four thousand feet. It is assumed by Mr. Hull, by the commissioners and most other authorities that this rock temperature of one hundred sixteen degrees will limit the possibilities of coal mining. At the average prices of the last three years or the prospective prices of the next three years this temperature may be, like difficulties of the thin seams, an insurmountable barrier, but I contend that at higher prices we may work coal at this, and even far higher rock temperatures, that it matters not how high the thermometer rises as we descend, we shall still go lower and still get coal so long as prices rise with the mercury. In this condition, and I have no doubt that coal may be worked where the rock temperature shall reach or even exceed two hundred twelve degrees. I do not say that we shall actually work coal at such depths, but if we do not, the reason will be not that the thermometer is too high, but that prices are too low. In other words, value not temperature will determine the working limits. Dr. Leafchild, in the last number of the Edinburgh Review, in discussing this question, tells us that the normal heat of our blood is ninety-eight degrees, and fever heat commences at one hundred degrees, and the extreme limit of fever heat may be taken at one hundred twelve degrees. Dr. Thudakam, a physician who has specially investigated this subject, has concluded from experiments on his own body at high temperatures that at a heat of one hundred forty degrees no work whatever could be carried on, and that at a temperature of from one hundred thirty degrees to one hundred forty degrees only a very small amount of labour, and that at short periods, was practicable, and further that human labour daily and at ordinary periods is limited by one hundred degrees of temperature as a fixed point, and then the air must be dry, for in moist air he did not think men could endure ordinary labour at a temperature exceeding ninety degrees. It may be presumptuous on my part to dispute the conclusions of a physician on such a subject, but I do so nevertheless, as the data required are simple practical facts such as are better obtained by furnace working than by sick room experience. During the hottest days of the summer of eighteen sixty-eight I was engaged in making some experiments in the reheating furnaces at Sir John Brown and Company's works, Sheffield, and carried a thermometer about with me which I suspended in various places where the men were working. At the place where I was chiefly engaged, a corner between two sets of furnaces the thermometer suspended in a position where it was not affected by direct radiations from the open furnaces stood at one hundred twenty degrees while the furnace doors were shut. The radiant heat to which the men themselves were exposed while making their greatest efforts in placing and removing the piles was far higher than this, but I cannot state it not having placed the thermometer in the position of the men. In one of the Bessemer pits the thermometer reached one hundred forty degrees and men worked there at a kind of labour demanding great muscular effort. It is true that during this same week the puddlers were compelled to leave their work, but the tremendous amount of concentrated exertion demanded of the puddler in front of a furnace which during the time of removing the balls radiates a degree of heat quite sufficient to roast a sirloin of beef if placed in the position of the puddle's hands. It is beyond comparison with that which would be demanded of a collier working even at a depth given a theoretical rock temperature of two hundred twelve degrees and aided by the coal cutting and other machinery that sufficiently high prices would readily command. In some of the operations of glass making the ordinary summer working temperature is considerably above one hundred degrees and the radiant heat to which the workmen are subjected far exceeds two hundred twelve degrees. This is the case during a pot setting and in the ordinary work of flashing crown glass. As regards the mere endurance of a high temperature the well-known experiments of Blagden, Sir Joseph Banks and others have shown that the human body can endure for short periods a temperature of two hundred sixty degrees Fahrenheit and upwards. My own experience of furnace work and of Turkish Baths quite satisfies me that I could do a fair day's work of six or eight hours in a temperature of one hundred thirty degrees Fahrenheit, provided I were free from the encumbrances of clothing and had access to abundance of tepid water. This in a still atmosphere, but with a moving current of dry air capable of promoting vigorous evaporation from the skin I suspect that the temperature might be ten or fifteen degrees higher. I enjoy ordinary walking exercise in a well-ventilated Turkish bath at one hundred fifty degrees and can endure it at one hundred eighty degrees. In order to obtain further information on this point I have written to Mr. Tindall the proprietor of the Turkish Baths at Newington Butts. He is an architect who has had considerable experience in the employment of workmen and in the construction of Turkish Baths and other hot air chambers. He says, shampooers work in my establishment from four to five hours at a time in a moist atmosphere at a temperature ranging from one hundred five degrees to one hundred ten degrees. I have myself worked twenty hours out of twenty-four in one day in a temperature over one hundred ten degrees. Once for one half hour I shampooed in one hundred eighty-five degrees. At the enamel works in Pimlico according to Mr. McKenzie men work daily in a heat of over three hundred degrees. The moment a man working in a one hundred ten degree heat begins to drink alcohol his tongue gets parched and he is obliged to continue drinking while at work and the brain gets so excited that he cannot do half the amount. I painted my skylights taking me about four hours at a temperature of about one hundred forty-five degrees. Also the hottest room skylights which took me one hour coming out at intervals for a cooler at a temperature of one hundred eighty degrees. I may add in conclusion that a man can work well in a moist temperature of one hundred ten degrees if he perspires freely. The following by a writer whose testimony may be safely accepted is extracted from an account of ordinary passenger ships of the Red Sea in the illustrated news of November nine eighteen seventy-two. The temperature in the stoke hole was one hundred forty-five degrees. The floor of this warm region is close to the ship's keel so it is very far below. There are twelve boilers six on each side each with a blazing furnace which has to be opened at regular intervals to put in new coals or to be poked up with long iron rods. This is the duty of the poor wretches who are doomed to this work. It is hard to believe that human beings could be got to labor under such conditions yet such persons are to be found. The work of stoking or feeding the fires is usually done by Arabs while the work of bringing the coal from the bunkers is done by Sidi Walas or Negroes. At times some of the more intelligent of these are promoted to the stoking. The Negroes who do this kind of work come from Zanzibar. They are generally short men with strong limbs, round bullet heads, and the very best of good nature in their dispositions. Some of them will work half an hour in such a place as the stoke hole without a drop of perspiration on their dark skins. Others particularly the Arabs, when it is so hot as it often is in the Red Sea, have to be carried up in a fainting condition and are restored to animation by dashing buckets of water over them as they lie on deck. Section 23 of Science in Short Chapters. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org. Science in Short Chapters by W. Matiu Williams. Section 23. It must be remembered that the theoretical temperature of 116 degrees at 4,000 feet, the 133 degrees at 5,000 feet, or the 150 degrees at 6,000 feet are the temperatures of the undisturbed rock. But this rock is a bad conductor of heat whose surface may be considerably cooled by radiation and convection, and therefore we are by no means to regard the rock temperature as that of the air of the roads and workings of the deep coal pits of the future. It is true that the Royal Commissioners have collected many facts showing that the actual difference between the face of the rocks of certain pits and the air passing through them is but small. But these data are not directly applicable to the question under consideration for the three following reasons. First, the comparisons are made between the temperature of the air and the actual temperature of the opened and already cooled strata. While the question to be solved is the difference between the theoretical temperature of the unopened earth depths and that of the air in roads and workings to be opened through them. Second, the cooling effect of ventilation must, as the commissioners themselves state, increase in a ratio which somewhat exceeds the ratio of the difference between the temperature of the air and that of the surrounding surface with which it is in contact. Thus the lower we proceed, the more and more effective cooling must a given amount of ventilation become. Thus, the lower we proceed, the more and more effectively cooling must a given amount of ventilation become. The third and by far the most important reason is that in the deep mining of the future special means will be devised and applied to the purpose of lowering the temperature of the workings. That as the descending efforts of the Collier increase with the ascending value of the coal, a new problem will be offered for solution and the method of working coal will be altered accordingly. In the cases quoted by the commissioners, the few degrees of cooling were affected by a system of ventilation that was devised to meet the requirements of respiration and not for the purpose of cooling the mine. It would be very presumptuous for anyone in 1873 to say how this special cooling will actually be affected, but I will nevertheless venture to indicate one or two principles which may be applied to the solution of the problem. First of all it must be noted that very deep mines are usually dry and there is good reason to believe that before reaching the commissioners limit of 4,000 feet dry mining would be the common and at and below 4,000 feet the universal case. At present we usually obtain coal from water-bearing strata and all our arrangements are governed by this very serious contingency. With water removed the whole system of coal mining may be revolutionized and thus the aspect of this problem of cooling the workings would become totally changed. Those who are acquainted with the present practice of mining are aware that when an estate is taken and about to be worked for coal the first question to be decided is the dip of the measures in order that the sinking may be made on the deep of the whole range. The pits are not sunk at that part of the same range where at first sight the coal appears the most accessible but on the contrary at the deepest part it is then carried on to some depth below the coal seam which is to be worked in order to form a sumpf or receptacle from which the water may be wound or pumped. The necessity for this in water-bearing strata is obvious enough if the collier began at the shallowest portion of his range and attempted to proceed downwards he would be drowned out unless he worked as a coal diver rather than a coal miner. By sinking in the deep he works upwards away from the water which all drains down to the sumpf from which it is pumped. The modern practice is to sink a pair of pits both on the deep and within a short distance of each other. The object of the second is ventilation. By contrivances which I need not hear detail the air is made to descend one of the pits the downcast shaft then to traverse the roads and workings wherein ventilation is required and returned by a reverse route to the upcast shaft by which it ascends to the surface. Thus it will be seen that whenever the temperature of the roads and workings exceeds that of the outer atmosphere the air currents have to be forced to travel through the mine in a direction contrary to their natural course. The cooler air of the downcast shaft has to climb the inclined roads and then after attaining its maximum temperature in the fresh workings must descend the roads till it reaches the upcast shaft. The cool air must rise and the warmer air descend. What then would be the course of the mining engineer when all the existing difficulties presented by water bearing strata should be removed and their place taken by a new and totally different obstacle namely high temperature. Obviously to reverse the present mode of working to sink on the upper part of the range and drive downwards in such a system of working the ventilation of the pit will be most powerfully aided or altogether affected by natural atmospheric currents. An upcast once determined by artificial means it will thereafter proceed spontaneously as the cold air of the downcast shaft will travel by a descending road to the workings and then after becoming heated will simply obey the superior pressure of the heavy column behind and proceed by an upward road to the upcast shaft as the impelling force of the air current will be the difference between the weight of the cool column of air in the downcast shaft and roads and the warm column in the upcast. The available force of natural ventilation and cooling will increase just as demanded i.e. it will increase with the depth of the workings and the heat of the rocks. A mining engineer who knows what is actually done with present arrangements will see at once that with the above stated advantages a gale of wind or even a hurricane might be directed through any particular roads or long wall workings that were once opened. Let us suppose the depth to be 5000 feet the rock temperature at starting 133 degrees and that of the outer air 60 degrees we should have a torrent of air 73 degrees cooler than the rocks rushing furiously downwards then past the face of the heated strata and absorbing its heat to such an extent that the upcast shaft would pour forth a perpetual blast of hot air like a gigantic furnace chimney. But this is not all. The heat and dryness of these deep workings of the future place at our disposal another and still more efficient cooling agency than even that of a hurricane of dry air ventilation. In the first part of the sinking of the deep shafts the usual water bearing strata would be encountered and the ordinary means of tubbing or coffering would probably be adopted for a temporary convenience during sinking. Doorways however would be left in the tubbing at suitable places for tapping at pleasure the wettest and most porous of the strata. Streams of cold water could thus be poured down the sides of the shaft which on reaching the bottom would flow by a downhill road into the workings. The steam of air rushing by the same route and becoming heated in its course would powerfully assist the evaporation of the water. The deeper and hotter the pit the more powerful would be these cooling agencies. As the specific heat of water is about five times that of the coal measure rocks or the coal itself every degree of heat communicated to each pound of water would abstract one degree from five pounds of rocks. But in the conversion of water at sixty degrees into vapor at say one hundred degrees the amount of heat absorbed is equivalent to that required to raise the same weight of water about one thousand degrees and thus the effective cooling power on the rock would be equivalent to five thousand degrees. The workings once opened I assume as a matter of course that by this time pillar and stall working will be entirely abandoned for long wall or something better. There would be no difficulty in thus pouring streams of water and torrents of air through the workings during the night or at any suitable time preparatory to the operations of the miner who long before the era of such deep workings will be merely the director of coal cutting and loading machinery. Given a sufficiently high price for coal at the pits mouth to pay wages and supply the necessary fixed capital I see no insupportable difficulty so far as mere temperature is concerned in working coal at double the depth of the Royal Commissioner's limit of possibility. At such a depth of eight thousand feet the theoretical rock temperature is one hundred eighty three degrees. By the means above indicated I have no doubt that this could be reduced to an air temperature below one hundred ten degrees that at which Mr. Tindall's shampooers ordinarily work. Of course the newly exposed face of the coal would have its initial temperature of one hundred eighty three degrees but this is a trivial heat compared to the red hot radiant surfaces to which puddlers, shinglers, glass makers, etc. are commonly exposed. Divested of the encumbrance of clothing with the whole surface of the skin continuously fanned by a powerful stream of air which during working hours need be but partly saturated with vapor a sturdy Midland or North countrymen would work merrily enough at short hours and high wages even though the newly exposed face of coal reached two hundred twelve degrees for we must remember that this new coal face would only correspond to the incomparably hotter furnace doors and fires of the steamship stoke holes. The high temperature at eight thousand or even ten thousand feet would present a really serious difficulty during the first opening of communications between the two pits. A spurt of brave effort would here be necessary and if anybody doubts whether Englishmen could be found to make the effort let him witness a pot setting at a glass house. Negro labour might be obtained if required but my experience among English workmen leads me to believe that they will never allow Negroes or any others to beat them at home in any kind of work where the wages paid are proportionate to the effort demanded. If I am right in the above estimates of working possibilities our coal resources may be increased by about forty thousand millions of tons beyond the estimate of the commissioners. To obtain such an additional quantity will certainly be worth an effort and unless we suffer a far worse calamity than the loss of all our minerals namely a deterioration of British energy the effort will assuredly be made. I have said repeatedly that it is not physical difficulties but market value that will determine the limits of our coal mining. This like all other values is of course determined by the relation between demand and supply. Fuel being one of the absolute necessaries of life the demand for it must continue so long as the conditions of human existence remain as at present and the outer limits of the possible value of coal will be determined by that of the next cheapest kind of fuel which is capable of superseding it. We begin by working the best and most accessible seams and while those remain in abundance the average value of coal will be determined by the cost of producing it under these easy conditions. Directly these most accessible coal seams cease to supply the whole demand. The market value rises until it becomes sufficient to cover the cost of working the less accessible and the average value will be regulated not by the cost of working what remains of the first or easy mines but by that of working the most difficult that must be worked in order to meet the demand. This is a simple case falling under the well-established economic law that the natural or cost value of any commodity is determined by the cost value of the most costly portion of it. Thus the only condition under which we can proceed to sink deeper and deeper is a demand of sufficient energy to keep pace with the continually increasing cost of production. This condition can only be fulfilled when there is no competing source of cheaper production which is adequate to supply the demand. The question then resolves itself into this. Is any source of supply likely to intervene that will prevent the value of coal from rising sufficiently to cover the cost of working the coal seams of four thousand feet and greater depth? Without entering upon the question of peat and wood fuel, both of which will for some uses undoubtedly come into competition with British coal as it rises in value, I believe that there are sound reasons for concluding that our London fireplaces and those of other towns situated on the seacoast and the banks of navigable rivers will be supplied with transatlantic coal long before we reach the commissioner's limit of four thousand feet. The highest prices of last winter, if steadily maintained, would be sufficient to bring about this important change. Temporary upward jerks of the price of coal have very little immediate effect upon supply as the surveying, conveyance, boring, sinking and fully opening of a new coal estate is a work of some years. The Royal Commissioners estimate that the North American coal fields contain an untouched coal area equal to seventy times the whole of ours. Further investigation is likely to increase rather than diminish this estimate. An important portion of this vast source of supply is well situated for shipment and may be easily worked at little cost. Hitherto the American coal fields have been greatly neglected, partly on account of the temptations to the agricultural occupation which are afforded by the vast area of the American continent, and partly by the barbarous barriers of American politics. Large amounts of capital which under the social operations of the laws of natural selection would have been devoted to the unfolding of the vast mineral resources of the United States are still wastefully invested in the maintenance of protectively nursed and sickly imitation of English manufacturers. When the political civilization of the United States becomes sufficiently advanced to establish a national free trade policy, this perverted capital will flow into its natural channels and the citizens of the states will be supplied with the more highly elaborated industrial products at a cheaper rate than at present by obtaining them in exchange for their super abundant raw material from those European countries where population is overflowing the raw material supplies. When this time arrives, and it may come with the characteristic suddenness of American changes, the question of American versus English coal in the English markets will reduce itself to one of horizontal versus vertical difficulties. If at some future period the average depth of the Newcastle coal pits becomes three thousand feet greater than those of the pits near the coast of the Atlantic or American lakes, and if the horizontal difficulties of three thousand miles of distance are less than the vertical difficulties of three thousand feet of depth, then coals will be carried from America to Newcastle. They will reach London and the towns on the south coast before this. That is, when the vertical difficulties at Newcastle plus those of horizontal traction from Newcastle to the south exceed those of eastward traction across the Atlantic. As the cost of carriage increases in a far smaller ratio than the open ocean distance, there is good reason for concluding that the day when London houses will be warmed by American coal is not very far distant. We in England who have outgrown the pernicious folly of protecting native industry will heartily welcome so desirable a consummation. It will render unnecessary any further inquiry into the existence of London coal rings or combinations for restricted output among colliers or their employers. If any morbid impediments to the free action of the coal trade do exist, the stimulating and purgative influence of foreign competition will rapidly restore the trade to a healthy condition. The effect of such introduction of American coal will not be to perpetually lock up our deep coal nor even to stop our gradual progress towards it. We shall merely proceed downwards at a much slower rate for in America as with ourselves the easily accessible coal will be first worked and as that becomes exhausted the deeper more remote thinner and inferior will only remain to be worked at continually increasing cost. When both our own and foreign coal cost more than peat or wood or other fuel, then and therefore will coal become quite inaccessible to us and this will probably be the case long before we are stopped by the physical obstacles of depth, density or high temperature. As this rise of value must of necessity be gradual and as the superseding of British by foreign coal as well as the final disuse of coal will gradually converge from the circumference towards the centres of supply from places distant from coal pits to those close around them. We shall have ample warning and opportunity for preparing for the social changes that the loss of the raw material will enforce. The above quoted writer in the Edinburgh review expresses in strong and unqualified terms an idea that is very prevalent in England and abroad. He says that the course of manufacturing supremacy of wealth and of power is directed by coal. That wonderful mineral of the possession of which Englishmen have thought so little but wasted so much is the modern realisation of the philosopher's stone. This chemical result of primeval vegetation has been the means by its abundance of raising this country to an unprecedented height of prosperity and its deficiency might have the effect of lowering it to slow decline. It raises up one people and casts down another. It makes railways on land and paths to the sea. It founds cities, it rules nations, it changes the course of empires. The fallacy of these customary attributions of social potency to mere mineral matter is amply shown by facts that are previously stated by the reviewer himself. He tells us that the coal fields of China extend over an area of 400,000 square miles and a good geologist Baron von Richthofen has reported that he himself has found a coal field in the province of Hunow covering an area of 21,700 square miles, which is nearly double our British coal area of 12,000 square miles. In the province of Shanxi the Baron discovered nearly 30,000 square miles of coal with unrivaled facilities for mining, but all these vast coal fields capable of supplying the whole world for some thousands of years to come are lying unworked. If the course of manufacturing supremacy of wealth and of power were directed by coal, then China, which possesses 33.3 times more of this directive force than Great Britain, and had so early a start in life, should be the supreme summit of the industrial world. If this solid hydrocarbon raises up one people and casts down another, the Chinaman should be raised 33 times and three tenths higher than the Englishman. If it makes railways on land and paths to the sea, the Chinese railways should be 33.3 times longer than ours and the tonnage of their mercantile marine 33.3 times greater. Every addition to our knowledge of the mineral resources of other parts of the world carries us nearer and nearer to the conclusion that the old idea of the superlative abundance of the natural mineral resources of England is a delusion. We are gradually discovering that, with the one exception of Tinstone, we have but little of any more than an average supply of useful ores and mineral fuel. It is a curious fact, and one upon which we may profitably ponder, that the poorest and the worst iron ores that have ever been commercially reduced are those of South Staffordshire and the Cleveland District, and these are the two greatest iron-making centres of the world. There are no ores of copper, zinc, tin, nickel, or silver in the neighbourhood of Birmingham, nor any golden sands upon the banks of the reed, yet this town is the hardware metropolis of the world, the fatherland of gilding and plating, and is rapidly becoming supreme in the highest art of gold and silverwork. These and a multitude of other analogous facts abundantly refute the idea that the native minerals, the natural fertility, the navigable rivers, or the convenient seaports, determine the industrial and commercial supremacy of nations. The moral forces exerted by the individual human molecules are the true components which determine the resulting force and direction of national progress. It is the industry and skill of our workmen, the self-denial, the enterprise and organising ability of our capitalists that has brought our coal so precociously to the surface, and redirected for human advantage the buried energies of ancient sunbeams, while the fossil fuel of other lands has remained inert. The foreigner who would see a sample of the source of British prosperity must not seek for it in a geological museum or among our subterranean rocks. Let him rather stand on the surrey side of London Bridge from eight to ten a.m. and contemplate the march of one of the battalions of our metropolitan industrial army, as it pours forth in an unceasing stream from the railway station towards the city. An analysis of the moral forces which produce the earnest faces and rapid steps of these rank and file and officers of commerce will reveal the true elements of British greatness, rather than any laboratory dissection of our coal or iron stone. Fuel and steam power have been urgently required by all mankind. Englishmen supplied these once. Their urgency was primary and they were first supplied even though the bowels of the earth had to be penetrated in order to obtain them. In the present exceptional and precocious degree of exhaustion of our coal treasures we have the effect, not the cause, of British industrial success. If in a rudor age our greater industrial energy enabled us to take the lead in supplying the rudor demands of our fellow creatures, why should not a higher culture of those same abundant energies qualify us to maintain our position and enable us to minister to the more refined and elaborate wants of a higher civilization? There are other necessary occupations quite as desirable as coal digging, furnace feeding, and cotton spinning. The approaching exhaustion of our coal supplies should therefore serve us as a warning for preparation. Britain will be forced to retire from the coal trade and should accordingly prepare her sons for higher branches of business, for those in which scientific knowledge and artistic training will replace mere muscular strength and mechanical skill. We have attained our present material prosperity mainly by our excellence in the use of steam power. Let us now struggle for supremacy in the practical application of brain power. We have time and opportunity for this. The exhaustion of our coal supplies will go on at a continually retarding pace. We shall always be approaching the end, but shall never absolutely reach it, as every step of approximation will diminish the rate of approach, like the everlasting process of reaching a given point by continually halving our distance from it. First of all we shall cease to export coal. Then we shall throw up the most voracious of our coal consuming industries, such as the reduction of iron ore in the blast furnace, then copper smelting, and the manufacture of malleable iron and steel from the pig, and so on progressively. If we keep in view the natural course and order of such progress, and intelligently prepare for it, the loss of our coal need not, in the smallest degree, retard the progress of our national prosperity. If, however, we act upon the belief that the advancement of a nation depends on the mere accident of physical advantages, if we fold our arms and wait for Providence to supply us with a physical substitute for coal, we shall become Chinaman, minus the unworked coal of China. If our educational efforts are conducted after the Chinese model, if we stultify the vigor and freshness of young brains by the weary dull and useless cramming of words and phrases, if we poison and pervert the growing intellect of British youth by feeding it upon the decayed carcasses of dead languages and on a feet and musty literature, our progress will be proportionately China word. But if we shake off that monkish inheritance, which leads so many of us blindly to believe that the business of education is to produce scholars rather than men, and direct our educational efforts towards the requirements of the future rather than the traditions of the past, we need have no fear that Great Britain will decline with the exhaustion of her coal fields. The teaching and training in schools and colleges must be directly and designedly preparatory to those of the workshop, the warehouse, and the office. For if our progress is to be worthy of our beginning, the moral and intellectual dignity of industry must be formally acknowledged and systematically sustained and advanced. Hitherto, we have been the first and the foremost in utilizing the fossil forces which the miner has unearthed. Hereafter, we must in like manner avail ourselves of the living forces the philosopher has revealed. Science must become as familiar among all classes of Englishmen as their household fuel. The youth of England must be trained to observe, generalize, and investigate the phenomena and forces of the world outside themselves, and also those moral forces within themselves upon the right or wrong government of which the success or failure, the happiness or misery of their lives will depend. With such teaching and training the future generations of England will make the best and most economical use of their coal while it lasts, and will still advance in material and moral prosperity in spite of its progressive exhaustion.