Light Science for Leisure Hours

uld one day depend,-or seem to depend,-on her stores of coal, a mineral then regarded as only an73 unpleasan

never did, no

roud foot of

rst did help t

ed to acknowledge. Saxon steadiness and Norman energy have doubtless played their part in placing Britain in the position she now holds; but whatever may have been the case in past ages of our history, it is certain that at present there is much truth in Liebig's assertion that England's power is in her coal. The tim

t important manner on the subject of England's coal-supply. For five years fifteen eminent Commissioners have been engaged in examining the available evidence respecting the stores of coal contained in the various coal-fields of Great Britain. Their inquiries were commenced soon after the time when the fears of the co

nd should drift unawares into what he called 'bituminous bankruptcy.' At that time the quantity of coal raised annually in England amounted to but about forty millions of tons. Ten years later the annual yield had risen to about fifty millions of tons; and then another warning voice was r

t we have already drawn from our choicest mines a far larger quantity of coal than has been raised in all other parts of the world put together; and the time is not remote when we shall have to encounter the disadvantages of increased cost of working and diminished value of produce.' Then he summed up the state of

the opinion that South Wales alone could supply all England with coals for 500 years. Mr. R. C. Taylor, of the Geological Society

n one year, then Mr. Stanley Jevons points out that instead of that amount, 10,326 would be sold in the next; and so far we may suppose that the other view would agree with his. But in the next, or third year (always remembering, however, that we must take one year with another), the increase of 326 tons would not be merely doubled, according to Mr. Stanley Jevons; that is, the consumption would not be only 10,652 tons:-the 10,000 of the second year would be replaced by 10,326 tons in the third year, and the remaining 326 would be increased by 3? tons for each hundred, or by rather more than 10? tons; so that in all there would be 10,662? tons, instead of 10,652. Now the difference in this third year seems small, though when it is applied to about nine thousand times 10,000 tons it is by no means small, amounting in fact to 95,000 tons; but when the principle is extended to sequent years its effects assume paramount importance. The small increase is as the small increase of a farthing for the78 second horseshoe-nail in the well-known problem. The effects, after a few years have passed, correspond to the thousands of pounds by which the last shoe-nails of that problem increase the cost of the horse. As Mr. Leonard Lemoran points

ed rate of increase could not possibly be maintained beyond a certain epoch, simply because there would not be enough men to work the coal mines to the extent required. But, regarding the increase as indicating the requirements of the kingdom, it would matter little whether the necessary supply failed for want of coal or for want of the means of raising the coal. In other words, removing the question from

result of a stethoscopic examination. The power of the nation residing-for the nonce at least-in her coal, the enforced consumption of coal at a rate which cannot be maintained (from whatever cause), means to all intents and purposes the decline and approaching demise of England's power as a nation. Furthermore, apart

increase as that, which has taken place during the last five years,' wrote an excellent practical authority, 'cannot continue for the next ten years,'-far less, therefore, that increasing rate of increase which Mr. Jevons had assumed. The same writer went farther even than this. For, after pointing out that the exportation of coal would p

preceding years, and adopted instead an increase of 3? per cent. year by year, taking one year with another. His own calculations gave for this year 1871 a consumption of 118 millions of tons,-an enormous increase on the annual consumption when he wrote. According to the view he rejected, the consumption for the year 1871 is easily computed, though slightly different results will be obtained, according to the year we choose to count from. The annual increase above mentioned gives an increase of 24,034,240 tons in ten years, and if we add this amount to the consumption in 1861 (83,635,214 tons) we obtain for the year 1871 a consumption of 107,669,454 tons. On

be regarded as surprisingly close. Remembering the conclusion to which Mr. Jevons came with respect to the period for which our coal stores would last, and noticing the close agreement thus far between his anticipations and the result, we can well understand the warning tone of the report issued by the Commissioners.83 'Every hypothesis,' they say, 'must be speculative, but it is certain that if the present rate of increase in the consumption

t, or to an even greater depth. 'The difficulties in the way of deep mining,' wrote Mr. Lemoran in 1866,84 'are mere questions of cost. It is important to notice that the assumption of 4,000 feet as the greatest depth to which coal can be worked, on account of the increase of temperature, is purely voluntary. The increase has been calculated at a rate for which there is no authority; and while we are saying our coal-beds cannot be worked below 4,000 feet, a colliery in Belgium has nearly approached that depth, and no inconvenience is experienced by the miners.' But t

well to regard the more prom

ncrease with the increase of our population, of our means of communication within our own country as well as with foreign countries, and so on. But all these causes of increase are now growing in activity at a rate which must inevitably diminish. Our population cannot increase beyond a certain extent, because the extent of the country will suffice for but a certain number of inhabitants. If emigration do not prevent increase beyond that number, other causes will, or else a much more serious evil than the exhaustion of all our coal stores awaits the country. Again, the requirements of inland communication will before long be so far met that no such rapid extension as is now in progress will be called for. After convenient communication has been established between all parts of the country-whether the process require the formation of new lines or of new services-no important increase can be required. As regards our commerce, its increase depends necessarily on the increase at present going86 on in the requirements of the country. Year by year Britain has a larger population, and the average requirements of each member of the population are also increasing. But we have seen that the increase of her population is necessarily limited; and although the increase of the requirements of her people may not be (strictly speaking) limited, yet it is manifest that, inasmuch as that increase depends on causes

esent population, we can scarcely believe that 1,440 millions will be needed in 1950, unless we suppose that the population of Britain will be twelve times greater than at present; or that the population will be even greater than this, since the consumption of coal upon our railways could scarcely be expected

ily expressed so as to accord with the mortality during those weeks, and perhaps two or three following weeks. But if such a law were extended indefinitely it might be found to imply nothing short of the complete desolation of the country by cholera, within the space of a few months. Thus, if the deaths (from cholera) in five successive weeks were 20, 27, 35, 47, and 63,-numbers corresponding with the general characteristics of cholera mortality in the

l be 2,000 millions of tons, or that the total consumption during the next 110 years will be 100,000 millions of tons. We might almost as safely infer that because a growing lad requires su

ll not rise to 150 or 200 or even 250 millions of tons per annum, or to point to any definite stage at which the present increasing rate of increase will be changed first into uniform (or arithmetical) increase, and thence into a decreasing rate of increase. But it appears to me that no question can exist that these changes will take place. We might even go farther, and regard it as all but certain that the time will come when there will be no annual increase. Nay, unless the history of t

e that that limit will be approached by a much gentler gradient, so to speak, than the same consumption as attained on Mr. Jevons's assumption. According to his view, in fact, an annual consumption of 350 millions of tons per annum will be attained early in the twentieth century; but according to the theory which sets such a consumption as the highest ever to be attained, we should place its attainment several hundreds of years later. This is a vague statement, I admit, but the very fact on which I am mainly insisting is this, that the evidence at present in our hands is insufficient as a basis of exact calculation. Now, if we set 500 years hence as the time when the annual consumption of coal will have reached the above enormous amount, we should set the total consumption during those centuries at about one-half that due to an annual91 consumption of 350 millions of tons. In that case there would still remain

, the result cannot be regarded as unfavourable. The more sanguine views entertained five or six years ago have not, indeed,, been fully j

he remarked, 'at which many of our pits are worked, and the vast extent of their lateral ramifications, make it more than ever necessary that we should secure the best mode of rendering the supply of pure air certain, regular, and safe. It is maintained that ventilating by machinery ensures these desiderata; that the nicety with which mechanical appliances may be regulated, the delicate adjustment of power of which they are capable, and the complete safety with which they may be worked, place them far before the system they are intended to supersede. The extent of our coal supply will be materially increased by the improvement of which this is a type.... It is probable that the ordinary means of ventilation-whether by furnace or fan-may be aided by a change in the force or agency employed for the purposes of

below may be safely worked. The idea seems somewhat daring; yet, after the feats of engineering which have been achieved in our day, there seems no valid reason for doubting that at least when the pressure of a failing coal supply begins to be felt, the means will be found94 for rendering these immense submarine coal stores available. As to the difficulty of transport, Mr. Elliot remarks that, according to his estimates, 'transport would neither be more costly nor more laborious than it has been in days gone by to convey coal the same distance after it was brought to the surface inland.' Th

the next few decades science will find the means of economising our coals in more ways than one. It does not indeed appear likely that any form of fuel will ever take the place of coal; but a portion of the work now derived from the consumption of coal may be expected to be derived in future

wastefulness in our day will then be felt, and none the less that for so many years there had been no failure in the supplies contained within the great subterranean storehouse.' It behoves us to consider thoughtfully the wants even of those distant eras. If the greatest good for the greatest number is to be regarded as the true rule for the conduct of intelligent beings, then unquestionably mere distance in point of time should not prevent us from an96ticipating the requirements of those remote descendants of ours. We should regard the consciousness of this duty and its performance as signs by which the superiority of our own over less civilised times is partly manifested. As man is in dignity higher than non-intelligent animals, in that he alone provides of his own forethought for the wants of his children, so our generation would be raised in dignity above preceding generations if it took intelligent charge of the wants of its remote descendants. We

Magazine, November