I will now allude to a diagram (fig. 35) which represents by a curve the yearly produce of barley, in bushels per acre, grown continuously on the same plots of ground for forty years, but with this difference, that one plot (represented by the upper curve) received 14 tons per annum per acre of farmyard manure, while the other, represented by the lower curve, has been unmanured continuously. This diagram has been constructed from figures given by Sir John Lawes and Sir Henry Gilbert in the 'Transactions of the Highland and Agricultural Society of Scotland' for 1895. I have replaced fractions by the nearest whole figure. The fluctuations of both these curves are very great, and it will be noticed that they are exactly parallel to each other. This teaches us that weather is the most important factor in agricultural success, and shows the extreme danger to the farmer of 'placing all his eggs in one basket,' as has been done by the so-called farmers of the Far West, who have attempted to grow wheat only by the process of scratching the prairie, without returning any dung to the soil, and many of whom have been financially swamped by the first bad season.

Taking the average of the forty years, it will be found that the produce of the manured land averaged 49 bushels per acre per annum, while the unmanured land gave only 16½ bushels.

I might have added to the diagram a third curve showing the produce of that plot of ground which, of all those manured with artificials, gave the highest yield. The yield of this plot for the whole forty years averaged 46 bushels, or only 3 bushels short of the average yield of the plot treated with farmyard manure. If, however, we take the average yield of the three plots for each of the four decades comprising the forty years, the value of the organic matter becomes very manifest. Thus the yield for each decade was with

It will be observed that the yield from artificial manuring only exceeded the yield from the farmyard plot in the first decade, when it showed an excess of 3·8 bushels. In the other three decades it was deficient by 2·1, 7·2, and 10·1 bushels.

The deficiency of the unmanured plot in each decade, as compared with the farmyard plot, was 22·7, 34·0, 37·3, and 39·0.

These figures are very convincing, and as practical agriculturists seem to be now agreed that farming is hopeless without an adequate amount of live-stock to furnish dung, no more need be said upon this head.

But is there no danger in using organic refuse, which may be infective and dangerous, as an application to the land? To this I should say emphatically 'No,' provided it be put in the upper layers of the soil, and the soil be tilled. Our organic refuse, when allowed to putrefy in water, and to trickle under pressure to our wells, or run direct into our sources of drinking-water, has turned millions of pounds into the pockets of members of my profession, but when rationally used as a top-dressing for the well-tilled soil it has never, that I am aware of, produced any harm.

I have tried to investigate this matter. Some five years ago I constructed a well five feet deep in the middle of a garden which is plentifully manured with all that is most loathsome to our senses. This well is lined to the very bottom with concrete pipes, further protected by an external coating of concrete; the junctions of the pipes are securely closed by cement, and there is a good parapet and efficient cover (see page 65 and figs. 22 and 23).

Now no water can possibly enter the well, except through the bottom. The water in it is clear and bright, and since its construction no mud has collected on the bottom. The sides of the pipes also remain absolutely clean, so much so that when, in 1895, I showed this well to a party of scientific friends, some of them dropped a hint that it had possibly been scrubbed in honour of their visit. This, however, was not the case.

The water from this well has been examined three times chemically, with the result that it has been pronounced free from organic impurities, and three bacteriological examinations have been made, with the result of showing a bacterial purity which is quite exceptional. The last examination was made by Dr. Cartwright Wood in November 1895, and showed a very high degree of bacterial purity. The water was specially examined by Dr. Wood for the presence of Bacterium Coli commune, but with negative results. Dr. Wood writes: 'The results are exceedingly satisfactory, and I must admit surprised me very much.' A surface-well on this pattern has lately been constructed in a village near Andover, and the results, as far as the appearance of the well and water is concerned, seem to be entirely satisfactory.

When people live crowded together in cities, the difficulties connected with the cleaning of the houses are very great. After the invention of the steam-engine it was found possible to supply even the top floors of the highest houses with an ample supply of water. We accordingly abolished the scavenger, and adopted a complete system of water-carried sewage. In this way our houses have been cleansed, and our rivers and surface-wells have been fouled, and it is difficult to say whether at present there be a balance of advantage or disadvantage. We have had epidemics of cholera and of typhoid, and it is almost certain that there is no one here present but has suffered in some way or other from the 'drains.'

The greatest drawback of this system is the fact that it encourages overcrowding of houses on inadequate areas, and, unfortunately, it is this fact which has rendered the system so popular. With water under pressure there is no need to provide houses with any back-door or back-yard, and there is no inconvenience in having excessively high buildings. The speculative builder, who has been relieved of all responsibilities in connection with sewage and water supply, has abundantly used his opportunities, and the happy ground-landlord has sold his land at large prices per square foot. We are shutting out the light and air more and more from our cities, and the crowding in the streets is making locomotion in them difficult. This overcrowding is a serious matter, and I will show what it means in London by means of a table and diagrammatic plan of the sanitary areas of London, with the mortality figures in the years 1892 and 1893, as calculated by Mr. Shirley Murphy, after due correction for abnormalities of age and sex distribution.

This table and plan (p. 144) shows at a glance that the mortality of London as a whole (taken as 1,000) is 14 or 15 per cent. higher than that of England and Wales, and that while some of the outlying districts, such as Hampstead, Lewisham, and Plumstead, have a mortality below that of England and Wales, the areas near the centre of London are all considerably above it; and some, such as the Strand, Holborn, St. George's-in-the-East, and Whitechapel, have a mortality as high as that of the worst manufacturing towns.

The danger of overcrowding is well shown by the explosive outburst of small-pox in Marylebone in 1894.

MORTALITY FIGURES

(Figures in small type show the population of the Sanitary Areas)

Fig. 36 represents part of the Asylums Board Map, in which each case of notified small-pox is shown by a black dot. This map shows that the outbreak was limited to two spots, one in Portland Town and one round Nightingale Street, Edgware Road, where the density of population, according to Mr. Charles Booth, is over 300 persons to the acre.

The Asylums Board is probably the most pauperising institution ever conceived, but we are such cowards in the presence of disease that financial and moral considerations have but little weight, provided the unclean be removed.

Another great drawback to the water-carriage system of sewage is the increasing difficulty with regard to water supply. Our needs per head per diem in the matter of water have gradually increased to something like forty gallons, which many experts consider to be none too much. In London the air is so foul that rain-water is valueless for domestic use, and the water of the surface wells is too poisonous to drink, because we have neglected what I believe to be the most important of the principles of sanitation, viz. the keeping of organic refuse, whether solid or liquid, on the surface. The humus is the most perfect purifier and the best of filters, in virtue of its physical conditions and the life that is in it. We deliberately take our filth to the under side of the filter, and then complain because our surface wells are foul. The water companies are masters of the situation. Water is not paid for, as a rule, in proportion to the quantity used, because Parliament in its wisdom has decided that thriftiness in the use of water is wicked. The grossly overburdened ratepayer is now pricking up his ears to listen to the prattle about Welsh water schemes at the cost of 38,000,000l., and is congratulating himself that he is only a leaseholder, and that his bondage is terminable in seven, fourteen, or twenty-one years at most. Water carriage, in which the carrier is some sixty times more heavy and twenty times more bulky than the thing to be carried, is economically ridiculous (except in places where Nature has provided enormous quantities of water), and involves everyplace where it is tried in ruinous debt. Let us take an illustration.

A suburban district having 27,000 persons on 7,000 acres of land, or a population of less than four to the acre, mainly engaged in market gardening, has in the last ten years borrowed 106,442l. for sewerage works. The only visible result to the inhabitants is that even country roads, with houses at ¼-mile or ½-mile intervals, have been dotted with foul-smelling manholes.

In 1894-5 the sum of 18,534l. 14s. 1d. was raised from rates, and of this there was spent 6,518l. 13s. 10d. for interest and repayment of sewerage loans, and 2,542l. 3s. 11d. for current expenses in connection with sewage. If to this be added one-third of the establishment charges (say 700l.), we reach a total of 9,860l., or more than half the sum received from rates.

The provision and maintenance of all the patent domestic gimcracks which water carriage involves, together with the necessarily increased bills for water paid by the householder, would probably double that sum, and we shall not be far wrong in saying that these 27,000 persons are spending 20,000l. a year for the purpose of throwing their capital into the Thames.

This doubling of rates has most seriously crippled the chief industry of the district, and the market gardeners feel severely the heavy extra charges which they are called upon to pay. These gentlemen, by putting much of the offal of great towns to its proper use, and converting it into food and wages for the poor, are doing a great work, but they are in a fair way of being ruined by the silly recklessness of our local governors.

On December 8, 1895, a writer in The Times pointed out that in 1895, as compared with 1890, 633,000 acres of land were either out of cultivation or had been converted into 'permanent pasture,' a term which implies a minimum cultivation. Of these lands there were in Essex over 31,000 acres, in Kent nearly 30,000, in Surrey 15,000, in Sussex 29,000, in Berks 20,000, in Bucks 11,500, Herts 7,600, Middlesex 5,500.

It is a noteworthy fact that in the eight counties nearest London, which provides for them an insatiable market, nearly 150,000 acres of land should have glided out of cultivation in the last five years. It is impossible not to believe that the local rates in places near London are the last straw upon the back of the agriculturist, who is ruinously taxed in order that his land may be starved. To show what suburban agriculturists have to bear in the way of local taxation I will quote from my little book, 'Essays on Rural Hygiene,'[4] a few figures showing what is paid by a gentleman who farms 200 acres of land, of which 15 are grass:

The social problems of the present day are many and complicated, and all of us have heard of 'Distressed Agriculture,' 'Pauperism,' 'The Aged Poor,' and the 'Unemployed.'

The agriculturist, who is being burdensomely taxed in order that his land may be starved, now has part of his rates paid for him out of the Imperial Exchequer. No one who knows the straits he is in will grudge him this relief. But the paying of local charges out of Imperial taxes has the inevitable result of making our 'Local Boards' more and more extravagant, because they have the spending without the trouble of raising money.

The reform most needed in the interest of agriculturists and others is to put an effectual check upon the extravagance and ostentation of Local Boards and District Councils, and to see that they spend no more money in any one year than they can raise in their districts. These bodies are now obliged to submit their accounts to a proper audit and to publish them, and it is hoped that the ratepayer will subject them to close criticism.

The policy of allowing persons who are elected for three years to raise loans and plunge a district into debt for a period of thirty years without one iota of personal responsibility is obviously dangerous. To allow reckless borrowing for the construction of works which are a source of expense and waste, and never of profit, would be called madness in private life.

Doubtless a seat on a Council which borrows money in lots of 100,000l. at a time affords a delightful amusement to the idle man, the busybody, the faddist, the philanthropist with a mission for fumbling in other persons' pockets, and the prophet who is ever anxious to borrow in order to provide for the future of which he is ignorant. Your prophet is the most dangerous of these persons, and instances will occur to the minds of most of us of municipalities which have been half ruined by over-sanguine persons endowed with speculative minds and persuasive tongues. The risk run by these persons is so small, be it remembered, that if an aggrieved ratepayer makes them defendants in an action, they enjoy the unique privilege of paying part of their costs and damages out of the successful plaintiff's pockets.

Most of the local borrowing in this country has been for works of sewerage, and although such works are financially ruinous, we are told that we get a dividend of 'Health.' This, however, is not true, and nobody could expect health to emerge from a system of which putrefaction and overcrowding are the chief characteristics.

The application of organic matter to well-tilled soil leads to positive gain and definite increase. The soil is the only permanent source of wealth in this world. And we are all of us absolutely dependent upon it for existence and happiness. The soil, if properly tilled, provides health as well as wealth, and be it remembered that in proportion to its productiveness so is the need of labour; and further, be it remembered that long after the eye is too dim and the hand too slow to keep time with steam machinery, the physical powers are amply sufficient for the cultivation of the land.

Many of our pressing social problems are inextricably linked with our duty to the soil, and any country in which the fertility of the soil does not increase cannot be rightly regarded as really in the van of civilisation and scientific progress. We are probably the wealthiest country on the globe, because for some time past we have been the hub of the entire financial world. Our success in one direction is no excuse for neglecting the more certain sources of wealth, and it is to be hoped that it will soon be regarded as evidence of neglect of our moral obligations to allow the land to drift out of cultivation.

CHAPTER VI
THE SOIL IN ITS RELATION TO DISEASE AND SANITATION[5]

In dealing with the relation of the earth to disease it behoves us to move with caution, and we shall do well at the outset to admit that there is very little knowledge of the subject which can be regarded as certain. We are in the land of conjectures, surmises, and plausible hypotheses, which perhaps are leading on to certain knowledge, but it will be necessary to check the dicta of the laboratories by experience gained outside of them. Such has always been the admirable custom in this country, where the labours of the pure scientist have been checked by that truly excellent staff of workers, the medical inspectors of the Local Government Board, to whom the world at large is more deeply indebted that perhaps it is aware. Before we blame the earth for causing us harm we must be sure that the facts, or alleged facts, of the bacteriologist are supported by the experience of the practical epidemiologist. Science unchecked by practice will certainly lead us astray in the future, as it has done in the past, and just as a 'lie which is half a truth is ever the blackest of lies,' so a new scientific fact imperfectly understood has potentialities for evil which are unbounded.

If we set aside for the present the question of malaria, which is undoubtedly primarily connected with certain soils, we have very little evidence that any other disease of practical importance is primarily connected with the soil. There appear to be two microbes which are present with tolerable constancy in the upper layers of the soil, and which, when applied to a raw surface or injected hypodermically, may cause tetanus and malignant œdema; but as yet we are without any evidence that either of these diseases can be caused by drinking water which has percolated through the soil, or can rise as a miasm from the soil. They concern the surgeon mainly, and from the point of view of epidemiology are unimportant.

Phthisis, or rather death from phthisis, which is not quite the same thing, is said to be more prevalent on damp soils than on dry ones, and it has further been said that the death-rate from this disease has been reduced in certain towns by sewerage. This statement is not universally accepted, and even if it be true it does not necessarily inculpate the soil because damp soils are cold, and patients with phthisis or any chronic lung trouble are very intolerant of cold and damp. It is very generally recognised that phthisis is prevalent in proportion to overcrowding, and that it is conveyed by tuberculous milk or meat seems to be certain as the result of recent experimental work. Any charge against the soil itself is as yet not proven.

Diphtheria has been said to be prevalent on certain soils, but this assertion is now discredited, and we recognise that the great cause of its spread is overcrowding. Its habitat, if it has any, outside the animal body is not yet known.

Anthrax, which is due to a spore-bearing organism, can certainly be conveyed to animals browsing on grass soiled by the dung or blood of infected animals. The bacilli seem to die in the carcase of a dead animal within three days after death; and as, for spore formation, the free access of air and a temperature of 70° F. are necessary, it is not likely that this goes on in the earth. Pasteur's assertion that anthrax spores may be brought to the surface by earthworms is discredited by Koch and others. Man, I believe, has never been infected with anthrax except by direct inoculation or, as in the wool-sorter, by inhaling spores from infected wool or hides. Clearly, animals should not be allowed to browse in an infected field, and such fields should, where possible, be ploughed up and converted from pasture into arable land. The danger of burying animals dead of anthrax is considered unworthy of credence by those eminent veterinary authorities, Professor Brown and Professor McFadyean, and the latter has shown that the process of putrefaction is fatal to the virulence of the tissues of the dead animal when these are inoculated into other animals or administered by the mouth.

Enteric fever and cholera bear a close resemblance to each other in their mode of spread, and they are both recognised in this country as mainly, if not entirely, water-borne diseases. Whether this be absolutely the case in the tropics I will not pause to discuss, because I am ignorant of the conditions of tropical life; but it is known that at present the water-borne theory, as against the air-borne theory, is receiving more and more support in India. That these diseases are produced in most cases by the direct infection of water by the excreta of infected patients is in Europe very generally acknowledged. The cholera epidemics of 1848, 1854, and 1866, and the more recent epidemic at Hamburg, strongly support the water-borne theory of cholera, and the enteric fever epidemics which afford similar evidence in this country have been so numerous that it is unnecessary to particularise. The spread of both these diseases seems to be favoured by conditions of filth and overcrowding, and the existence of a filthy and sodden condition of the soil has been often spoken of in connection with them. Nevertheless, there have been very few outbreaks of enteric fever in which the fact that cesspools, sewers, or underground middens have been in direct communication with the sources of water has not been detected. If, as seems highly probable, typhoid fever may be conveyed by sewer air, there is nothing improbable in the suggestion that it can be conveyed by the air of privies or middens in which fæces are allowed to putrefy. That typhoid fever poison can lurk in properly-tilled ground seems very unlikely, and I am not aware that such a thing has ever been suggested. Pettenkofer's statement, that epidemics of typhoid fever and cholera follow depressions of the ground water may be true for Munich, but it has not been materially supported in this country; and, in Budapest, Fodor has found that these diseases are more prevalent when the ground water is high. The variations of level in the ground water depend upon such a number of meteorological and other conditions, and give rise to so many and different effects, that even if Pettenkofer's statement be accepted it would not necessarily point to the earth as the natural habitat of the typhoid fever poison. Professor Lane Notter, in his summing up of this ground-water question, says[6]: 'It must, however, be borne in mind that it is not the ground itself which is the cause of the disease, but the impurities in the soil which the varying level of the ground water helps to set in action.' Now, no organic impurity can possibly reach the soil from the subsoil, which is purely inorganic. Any organic impurity which reaches the ground water must, therefore, come from above, and is due in the vast majority of cases to our mismanagement of organic refuse. Dr. Sims Woodhead[7] says that 'the deeper layers of the earth are frequently almost entirely free from micro-organisms, just as is the ground water.' Of course if the soil of a city be porous, and if there be a subterranean network of sewers interspersed with cesspools, this would (in the high probability that an average proportion of these contrivances leak) constitute a very great danger, but we must not blame the earth because we mismanage it. The earth, be it remembered, is our sole permanent source of wealth, and we must not needlessly quarrel with our bread-and-butter.

This world would not be habitable were it not for the humus with which its bare rocks are clothed. The humus is the living covering of the skeleton, and its formation has taken ages. The primitive bare rock which has been 'weathered' by the changing seasons gets clothed with a growth of lichen. This thin but rough covering entangles stray particles, and thus by its own decay affords a nidus for a stronger growth. This stronger growth, by chemical action and physical force, works further into the rock, on which the soaking rains and rending frosts have an increasing effect, and thus, partly by the disruption of the inorganic rock, and partly by the increase in ever-growing quantities of vegetable decay, the humus rises, as it were, 'on stepping-stones of its dead self' until it is able to afford footing and nourishment for the stately forest tree, and its fertility finally becomes sufficient to attract the attention of the husbandman. This humus, the loose, mainly organic covering of the rocks, is formed, as we have seen, by crumbling rocks from below and by the constant additions of dead organic matter which are deposited upon the surface. These additions of organic matter, be they in the form of dead animals, dead leaves, dung, or what not, become humified, and thus the stock of humus tends steadily to increase. The greater the stock of humus the greater the fertility, and the greater the fertility the greater will be the amount of dead organic matter to increase the stock of humus. The conversion of the dead organic matter into humus is a biological process, and is caused by the animals which live in the humus, and is perfected by the growth of fungi. On this account I ventured some years ago to speak of the humus as the 'Living Earth,' and I take it that no more important addition has ever been made to the stock of human knowledge than the recognition that the humus teems with life, and that its fertility and healthiness depend entirely upon biological processes. If the humus be sterilised, either by heat or antiseptics, it becomes absolutely barren. It was at one time supposed that the fertility of the soil depended mainly upon the process of nitrification, whereby nitrogenous organic matter is converted into soluble nitrates which are absorbed by the roots of plants, and there can be no doubt that these nitrifying organisms are most important. The causes of the fertility of the soil are probably far more complex than we suppose, and I think it may be said that we are as yet only upon the threshold of our knowledge with regard to them.

The phenomenon of 'symbiosis,' or the living together of chlorophyll-bearing plants with those which have no chlorophyll in so-called symbiotic community, where each partner works for its fellow's good as well as its own, is far more common than was supposed. Originally demonstrated in so-called lichens, which really consist of symbioses of fungi and algæ, it was next shown in the papilionaceous leguminosæ, whose nourishment appears to be largely dependent upon so-called bacterial nodules which grow upon their roots, and, according to my observations, more upon the superficial roots than those which run more deeply. In Oliver's edition of Kerner's 'Natural History of Plants'[8] will be found an account of symbioses between fungi and big flowering plants in which 'the division of labour consists in the fungus mycelium providing the green-leaved phanerogam with water and food-stuffs from the ground, whilst receiving in return from its partner such organic compounds as have been produced in the green leaves.' 'The union of two partners always takes place underground, the absorbent roots of the phanerogam being woven over by the filaments of a mycelium.... As the root grows onward the mycelium grows with it, accompanying it like a shadow.... The ultimate ramifications of roots of trees 100 years old and the suction roots of year-old seedlings are woven by the mycelial filaments in precisely the same manner.' It is stated that many plants only flourish in symbiotic community, and in this fact lies the explanation of the readiness of some plants to grow and flourish from cuttings put in sand, or from seedlings grown in nutritive solutions, while others, in the absence of the necessary fungi encircling their roots, cannot be made to strike root or flourish in this way. When it is stated that to the latter class belong oaks, beeches, firs, willows, poplars, rhododendrons, and heaths, the importance of symbiosis in this world will be readily understood. Now we know why it is that the gardener prizes leaf-mould in spite of its being comparatively poor in nitrogen as compared with guano. Leaf-mould is full of fungi, and in it the plant readily establishes its requisite symbiosis.

This great and astounding fact of symbiosis, of which we have only recently had cognisance, will serve to enforce the steadily growing opinion that the sphere of the chemist is in all living processes strictly limited. In estimating the value of artificial manures the chemist's dictum is of the greatest value, but his analysis when used to gauge the value of the living humus may be entirely misleading. The chemist has told us again and again that the quantity of nitrogen in humus and in earth-closet soil is, as compared with many artificial manures, comparatively small, and therefore the mistake has been made of regarding human fæces and the product of earth closets as of small manurial value. I believe that such a statement is most misleading, and on this point I claim to speak with no inconsiderable experience. For the past ten years I have cultivated a garden of about an acre and a quarter in extent in which the only manure used has been the excremental and other refuse of some twenty cottages with about 100 inhabitants. In August 1895 I invited a party of the British Medical Association to view that garden, and I think that none of my guests on that occasion will refuse to admit that the garden was as full of crops of one kind and another as a garden could well be. Dr. Voelcker, the chemist of the Royal Agricultural Society, whom I had the honour of numbering among my guests on that occasion, told me that he had never seen a piece of ground more fully stocked, and he very kindly went carefully round the garden with me to see if his experienced eye could detect any sign of sickness in the soil. I have never detected any such signs, and neither could he. The garden affords no evidence of being overdone with manure, and my belief is that it would take a great deal more. This ten years' experience has convinced me that human fæces constitute a manure of the greatest value, all analyses to the contrary notwithstanding. The probable explanation lies in the fact that the microbes extruded with the fæces are of great value in developing the fertility of the humus.

Many recent experiences in sanitation and in medicine force upon us the conclusion that the value of chemical analysis in biological questions is not final. Water which has been found to contain the bacillus of typhoid fever has passed the tests of the chemist, and there can be little doubt that in the past many samples of wholesome water have been condemned for containing the products, in the form of nitrates, of oxidised organic matter. Again, the action of toxins and antitoxins is quite beyond the reach of the chemist, and the marvellous results which have been obtained by administering thyroid extract teach us that in dietetics there is something which the chemist cannot gauge. Raw thyroid and cooked thyroid would give the same results on analysis, but how different is the physiological result! How different is the action of the carefully dried stomach of the calf in the form of rennet or pepsin as compared with a dish of tripe! These facts must force upon us the speculation that the same thing may produce very different effects according to the temperature to which it may have been artificially raised by drying under a vacuum or by cooking, and must drive us to the conclusion that although it may be advisable under certain circumstances to boil our milk or our water, it is possible that the act of cooking may change, we know not to what degree, the physiological action of the milk or water which has been thus treated. My experience tells me that the chemists are wrong when they say that human excreta are of small manurial value. Their analyses are doubtless right, but their conclusions are erroneous and very dangerously misleading. In this statement I should be supported by the whole of the 'Far Eastern' nations.

The ultimate manurial value of urine is doubtless very great, although when pure or nearly pure it is very deadly to herbage. The only satisfactory way of using urine as a manure is to imitate the farmer, by mixing it with an absorbent material, such as straw, sawdust, peat, earth, paper, cotton waste, wool waste, &c., placing it upon the surface of the ground and digging or ploughing it in.

The best evidence that the humus is alive is the fact that it breathes. The fungi which are destitute of chlorophyll absorb oxygen and give off carbonic acid, in this respect resembling animals and differing from the chlorophyll-bearing plants. The most easily obtained evidence of this is the fact that decaying refuse generates heat, a fact which is easily ascertained by using a thermometer. Thus I have at present in the garden of my cottage in the Thames Valley a heap of privet leaves intermixed with a quantity of fine twigs which give it great porosity and serve to admit a large quantity of air. On the morning of October 21 the temperature of the air was 39° F., and the temperature of the heap of leaves was 57° (18° more than the air). On October 22 there was a heavy cold rain with a cold easterly wind. On the morning of October 23 the temperature of the air was 40° and the temperature of the heap of leaves was 56°. On the night of October 23-24 there was (for the time of year) a very severe frost. My heap of leaves on the morning of the 24th was solidified on the surface by the frost, but the temperature of the interior was 53° while that of the air was 30° (an increase of 23° over the air). This heap, it should be stated, is only a small heap, and would all go into a big wheelbarrow. On the morning of October 24, after taking the temperature of this heap, I turned it over with a fork, putting the frozen top in the centre and altering the position of the constituents of the heap. A quarter of an hour later the temperature of the heap was found to be 32°, and at seven in the evening it was still at freezing-point, or only just above it. The night of October 24-25 was again very frosty, as many as 12° of frost having been registered at a house close by. At eight in the morning of the 25th, however, my heap of leaves showed a temperature of 40°, having risen 8° during this very cold night, and being 20° above the minimum cold recorded in the night. At 7 P.M. on the 25th the temperature of the heap was 42°, and the next morning, after a third very cold and frosty night, it had risen to 45°. The rise of temperature here was clearly due to the respiration of living things, and could not have been in any degree caused by absorption of sun heat. (Since the above was written autumn has come upon us, and the fallen leaves have been collected into a big heap. On November 15 the temperature of this heap was found to be 62° F., and a week later (November 22) had risen to 104° F.!) The fact that the humification of organic matter generates heat is a fact which is of enormous practical value to the gardener and farmer. The market gardens round London, which produce astounding crops and assimilate an enormous quantity of dung, are in a sense extended and mild hotbeds. One hopes that those who are advocating the burning of organic refuse will pause to think, however necessary such a process may be under certain circumstances, how great is the dispersion of energy which such a process involves and how much heat is lost which might otherwise be used for the stimulation of germination and growth in seeds and plants. One hopes also that those who would condemn as foul the humus which contains a large amount of carbonic acid will remember that this gas may only be an evidence of perfectly healthy and vigorous action. The important fact that the tillers of the soil are the most long-lived of all the laboring classes is one which must never be lost sight of.

That the humus breathes and generates an enormous quantity of carbonic acid precisely as an animal does is a fact which the agriculturist must ever bear in mind. Many of the operations of the farm have for their object the loosening of the soil and the admission of air to enable the respiratory processes to go on. Every farmer will tell you that the earlier he can get upon the ground to hoe his turnips the better will be the crop (other things being equal), and every farmer knows the advantage of thorough tillage. If the respiration of the humus is an important fact, it becomes very important indeed not to drown it. It stands drowning no better than a man does, but, like a man, it requires a requisite amount, but not too much, to drink. There can be no doubt that the failure, which is almost general, of so-called sewage farming arises through the drowning of the humus; and it must be borne in mind that sewage water consists to a very considerable extent of water which has been boiled, or is hard, deep well water, and has not the valuable quality of rain-water of containing some 2·5 volumes per cent. of atmospheric air dissolved in it. There can be little doubt that the great trouble to the sewage farmer is the excess of water which drowns the humus. When three or four ounces of excrement are mixed with 1,200 times their weight of water they run small chance of humification, and one must fear that the difficulties of the sewage farmer (financial or agricultural, or both) must increase with the magnificence and extravagance of the water-supply of the town the sanitary interests of which the sewage farm is intended to subserve. The evil effects of too much water have come before me lately in two very striking examples. While going over the experimental farm belonging to Mr. H. C. Stephens, M.P., at Cholderton, on Salisbury Plain, this autumn (which I did in company with a large number of practical agriculturists), there were here and there noticeable in the middle of fields having a uniform quality of soil, and which had been treated in identical fashions, certain large patches over which the growth of turnips, as compared with the rest of the fields was very defective. The explanation offered was that on these patches the animals had been folded in wet weather, that the dung had been trodden into the ground, and the soil had been hardened and consolidated by the trampling of the beasts. Under such conditions (air not being adequately admitted to the pores of the soil) the humification of the dung had been hindered and the crops stunted in consequence. This was a fact new to me, who am only an amateur agriculturist; but I may state that it was unanimously and unreservedly accepted as an adequate explanation by all the farmers present, who seemed to be perfectly familiar with the consequences of folding cattle in the wet. On the other hand, the most fertile patch of the whole farm was where the cattle had been folded for a fortnight continuously on the same spot during the severe frost of last winter, and had been fed upon food which was necessarily brought to them on that spot. The ground being as hard as iron could not be more consolidated by trampling, and with the advent of the thaw there was a general disruption of soil and dung, and humification went on rapidly in earth of which the pores had been opened by the beneficent effects of a deep frost, and which had received an amount of dung which was exceptionally great.

Another experience was a visit to a sewage farm belonging to a town in which brewing is the staple industry. This farm was large (nearly twice as big as at one time was considered necessary) and was composed of a very porous, gravelly soil in a high situation. The manager was an able man, and one felt that if success was to be obtained it was here. But the amount of water pumped on to this ground was exceptionally great, amounting at times to as much as 150 gallons per head of population per diem. The result can be imagined. The humus was drowned, and large tracts of the farm were as wet as a marsh, bore no crops, and never could be made to bear any under such conditions. As soon as it had been saturated it was ploughed up and saturated again, there being no time (let alone other considerations) to grow crops in face of the huge volumes of water which had to be dealt with. Those parts of the farm which were under cultivation grew enormous quantities of water-grass, a noxious weed, and altogether the agricultural aspects of this estate were as gloomy as could well be. As for the effluent, it was thick and turbid, and stunk like a dirty brewery. It was impossible to believe that the effluent had been rendered safe for discharge into a river, and its cost must have approached that of the beer which was sold in the adjoining town. The amount of water seemed to be the trouble here, and clearly the first duty of the municipality would be to divert directly into the river all the storm water and all the water which was used in enormous quantities for refrigerating purposes, and which, being perfectly wholesome, might go into the stream direct. A visit to the pumping-station of this municipality was most unpleasant for the nostrils, and left upon me the impression that the Local Government Board would do well to insist that all sewage committees should have a board-room at the pumping-station and another at the farm, and should be allowed to deliberate in no other place. The humification of excrement in the presence of such an overpowering amount of water is impossible, and I believe that municipalities which are now busy diverting storm water will have to go further and deal with excreta, domestic slop-water, and manufacturers' effluents on different and separate systems. I confess I should like to see water-closets dealt with on an independent system by a vacuum principle such as is advocated by Shone and Liernur. Manufacturers' refuse, which is liable to contain chemicals and antiseptics, is so likely to kill the humus by poison as well as by drowning that it seems impossible to deal with it on any one system, and it is to be hoped that with the advance of chemistry it may be increasingly possible to turn manufacturing effluents to profitable account.

It is now more than ten years ago since I first deliberately drew attention to the shortcomings of modern sanitary methods, and pointed out that the safe disposal of organic refuse was a question of which the biologist, rather than the engineer or chemist, would give us the solution. It is a hopeful sign of the times that engineers are now recognising this fact, thanks mainly to the teaching of the Board of Health in Massachusetts. The purification of sewage is wrought by the presence of living organisms on the filters; and for the due filtration of drinking-water it is now admitted that the filtering material must have a coating of living slime. These are facts which are now all but universally admitted.

Our go-ahead municipalities, formed on democratic lines, are more ostentatious than the worst of Roman emperors. The London County Council wished at one time to give 750,000l. for a site for its house! The central ideas of modern municipalism are the raising of loans and the sweating of the ratepayer. It must be remembered that there is no relation between magnificence and real efficiency. For example, in a town which I sometimes visit I am always interested by a stately pageant consisting of a huge conveyance weighing at least half a ton and looking like a cross between a railway truck and a hearse. This is drawn by a horse weighing 15 or 16 cwt., and this horse is guarded by two men weighing, perhaps, 12 st. apiece. Inside the hearse are eighteen huge pails weighing 40 lb. each, and inside the pails are the weekly excreta of ninety people, which should, if properly managed, certainly not weigh more than 200 lb. or 300 lb. In short, there are about 30 cwt. of gear for the removal of at most 3 cwt. of material. This cumbrous array works, it need hardly be said, at a funereal pace, and there can be no doubt that a lad with a hand-truck coming every day would do the work far more rapidly, efficiently, and cheaply.

It must be borne in mind that the fertility of the soil should bear a certain proportion to the density of population, and that the ability of land to support its population ought steadily to increase, especially if the population enjoys the blessings of free trade. I may perhaps best illustrate my meaning by referring again to the visit which I paid to the farm of Mr. H. C. Stephens, M.P. The down lands which comprise this district consist of a very few inches of humus overlying chalk, the herbage is scanty, and the population of animals (in relation to acreage) necessarily very small. One of the difficulties which the farmer has had to encounter in this district is the obtaining of sufficient water for his stock, and perhaps the most important work which Mr. Stephens has done is to sink a deep well in the chalk. This well, worked by a wind engine and provided with storage reservoirs, gives a supply of water which may be regarded as unlimited. With good water-supply, ample area, and the possibility of importing food which the neighbouring railway affords, it became possible to maintain a very large number of sheep, oxen, and horses for farm and breeding purposes. The animals are all folded, and the whole of their dung is returned to the soil, and the effect produced by this large addition of organic matter cannot fail to strike the visitor, who finds in spots where the herbage was previously so thin as to approach barrenness that he now has to wade knee-deep through a thick felt of grass. All over the farm the effect of adding this organic matter to the soil is everywhere apparent, and it is certain that the need of imported food-stuffs for the animals must diminish in proportion to the increase of fertility of the farm. This estate on Salisbury Plain realises, in fact, the utopia of which I have spoken in 'Rural Hygiene'[9]—i.e., a place where there are water-pipes but no sewer pipes. The indispensable water has by skilful but comparatively simple engineering been brought within easy reach of the human and animal population, but the organic excrements and other refuse, instead of being washed away into a neighbouring valley to poison the inhabitants there, are retained upon the soil to provide extra herbage, extra meat, extra work, and extra wages, with increased contentment and no loss of health. The increased fertility of the soil must have the effect of counteracting poverty and diminishing that charge upon the land known as the Poor-rate, and as for sanitary rates, the very essence of the progress I have been describing consists in the fact that there are none to pay. When the members of the local council in this utopia have mended the roads and paid for the school they may return with a clear conscience to their own business, instead of meddling with that of other people.

The fact that the potential increase of the fertility of the soil is to a certain extent proportioned to the increase of population is a political and economical fact of fundamental importance. The fertility of the soil of a country which imports millions of tons of food ought steadily to increase, and I believe that but for counteracting circumstances free trade ought to have benefited the farmer equally with all other classes of the community. If the enormous quantity of excremental and refuse matters due to free trade had been placed upon the land to increase the national stock of humus the fertility of the soil must have increased proportionately, and the fall in prices due to the competition of imported food would have been proportionately counteracted. If on the farm at Cholderton which I have been describing the well water had been used for washing all the excrement of the animals into the nearest river there could have been no increase of fertility of the soil, and the animals must have been dependent upon imported cake and other food-stuffs to a degree which would never vary, instead of, as at present, tending steadily to get less. Among the nostrums which have been suggested for the relief of agricultural distress are 'light railways,' but as imports and exports are apt to balance themselves, one would fear that the light railway, for every truss of hay or sack of corn which it conveys to the nearest junction, will bring back a frozen carcase of meat or its equivalent. If, however, these light railways (and the existing railways) can bring the refuse of the towns on to the land to increase the agricultural capital in the form of humus, the farmers will certainly have more to sell and our need of imported food (per head of population) will tend steadily to get less. Until—if I may use the expression—we make some serious effort to leave our imported 'cake' upon the land in a form in which it can be advantageously utilised, our needs for importation will never get less, and our state of scare as to the sufficiency of our Navy will get steadily worse as the population increases. It is very bad policy for railways to charge exorbitant rates for the conveyance of dung, because the less dung they import the less will be the export of produce on the return journey. It is impossible to doubt that the man who increases the fertility of the soil of a country deserves well of that country and should be encouraged by the State and his fellow-countrymen. Professor Otis Mason of Washington has gone so far as to say: 'The form of law which does not decrease the amount of taxation proportionally to the yield per acre is not in the line of progress.' And again: 'Any law which punishes a man with taxation for preventing waste, recuperating worn acres, or developing the latent resources of nature, is wicked.' There can be no doubt that taxation presses very hardly upon agriculturists, especially those whose land happens to be within the boundary of a 'progressive' corporation. I have mentioned (p. 149) a friend who farms 200 acres of land (of which fifteen are grass) in the Thames Valley who pays more than 300l. a year in imperial and local taxes. This is due to the fact that he is under the heel of a 'progressive' board, which, finding it can borrow money at 3 per cent., is making full use of its powers and is fast converting a pretty village into something scarcely distinguishable from Houndsditch.

We may now profitably turn to the consideration of Malaria, a disease which is undoubtedly connected with the soil and which has its habitat in the soil of certain places. Malaria requires for its development decaying organic matter, a high or moderately high temperature, and usually an excess of moisture. Tropical marshes are the elected seats of malaria, but not the exclusive seats, for it is known that certain rocks and arid plains, as well as the sandy estuaries of rivers, are liable to be malarious. The one thing which all, or almost all, malarious districts have in common is the fact that they are barren, or nearly so, uncultivated, and in many cases uncultivable. Malaria is rare in England, but once it was common, and we must not forget that James I. and Cromwell are both of them said to have been victims of this disease, which was rife in London in their time, especially in the Essex marshes and on the south side of the Thames, in Lambeth Marsh and the adjoining districts. An undrained country is uncultivable, and it has been found that drainage followed by cultivation has in this country enormously lessened the amount of malarious disease. Cultivation of land finishes the work begun by artificial drainage. The soil is dried and aërated by tillage, and the organic matter, when the humus is no longer drowned, is oxidised, and goes to nourish plants and trees, which effect an upward drainage no less important than the downward drainage, while the oxygen exhaled by the green leaves cannot but benefit the air of the locality. If we wish to keep clear of malaria in this country we must till the soil and so nourish the humus that its produce may be sufficiently valuable to bear the expense of any artificial drainage which it may be necessary to maintain. If the land of this country goes out of cultivation, as in places it seems to be doing, I see no reason why we or our successors should not witness a recrudescence of malarious disease in localities which are prone to develop it.

It will not be unprofitable in this connection to consider the history of the Roman Campagna. It is generally admitted that the Roman Campagna was not always the desolate waste which it ultimately became. It was prone to malaria, doubtless, but this was kept in check by the large farming population. It is not conceivable that in days when locomotion was slow a city could have attained the proportions and importance of Rome if it had been situated in the middle of a sterile and malarious plain. The neglect of agriculture began in the Augustan age, when Rome was at the zenith of her power, and it is worthy of note that Mæcenas is credited with having incited Virgil to write the 'Georgics' in order to direct, by this fascinating method, the attention of the Roman people to the neglected joys of agriculture. With the acquisition of fertile districts in Africa and elsewhere, not only did the need for home-grown commodities decrease, but it is probable that the profits of home farming decreased also. Corn was imported in enormous quantities, while the expenses connected with the defence of the Empire led to such a merciless taxation of the landholder that in self-defence he was obliged to allow his land to go out of cultivation, and thus escape from the brutal exactions of the tax-gatherer. According to Gibbon, within sixty years of the death of Constantine 320,000 acres of the district of Campania had become barren. Further, there can be no doubt that the Cloaca Maxima and other cloacæ sent to the Tiber much, if not all, of the organic refuse which should have been returned to the land. Finally, there can be little doubt that the extravagant water supply of ancient Rome must have had the effect of causing neglect of local wells, and as the water of the aqueducts was supplied to places in the Campagna as well as to Rome itself, the discontinuance of pumping must have helped to leave moisture in the soil at the same time that an extra supply from a distance was giving an additional quantity to it. As these great works of engineering did away with the necessity of manual labour, and as the barren land stood in no need of husbandmen, it is not to be wondered at that the problem of the unemployed grew urgent in Rome. We hear that in the later days of the Empire the masses congregated at the baths or waited whole days at the doors of the amphitheatre while they were fed with doles of bread or corn supplied from the public granaries. With a dense idle population and with barren and unwholesome surroundings the amenities of Rome as an imperial residence declined, and on this account it was probably that Diocletian seldom visited it; and one cannot but think that the social and sanitary conditions of the capital were among the causes which led Constantine to abandon it in favour of his new city on the Bosphorus. Finally, one is not surprised to hear that when Alaric took the city in the beginning of the fifth century he did so, not by direct assault, but by seizing the huge granaries and magazines at the Port of Ostia, and then offering to the unhappy Romans the choice of surrender or starvation. We are often asked to admire the Roman aqueducts, and Rome is not infrequently held up to us as a model to be copied. I fear we are copying her only too exactly, and I fear that equally with Rome we shall find out the futility of a brutal and reckless expenditure mainly directed towards the starvation of the soil and a senseless struggle with conditions imposed on us by Nature. I have heard it suggested that the cultivation of the soil of England is of no importance, that our islands are destined for residential and manufacturing purposes only, and that our sustenance is to depend entirely upon 'big-bellied argosies' bearing all the treasures of more fertile climes. But the cultivation of the soil and the nurturing of the humus have important bearings upon questions other than food supply, and if we continue to starve the humus and to convey our filth beneath it instead of upon it, I fear that the cost of living in this country is likely to increase, while the pleasures of existence will diminish.

The moral of all that I have been saying is to the effect that to nourish the humus and to till it are the inexorable duty of the sanitarian. This simple duty is the key to plentiful food and a good supply of wholesome water. Nature is relentless, and will sooner or later destroy those who neglect to follow her inexorable laws. We used to say that 'the weakest' (morally, physically, and mentally) 'must go to the wall.' Now we use the expression 'survival of the fittest' to express the same idea. Nature does not relent, but man, in his commendable efforts towards philanthropy, endeavours to relent, and hence the principle underlying much modern sanitary work is the attempt to bring about the survival of the unfittest. If I may judge from the criticisms to which at one time and another the ideas which I have put forward have been subjected, I may conclude that the principles advocated are considered right, but that the lowest classes of our population are not to be trusted to safeguard to any extent the wholesomeness of their homes. Therefore we are all asked to come down to the level of the dirtiest and most careless, and our sanitary methods (in which there is too much of Hercules and too little of Minerva) do not admit of any encouragement being given to those living within a municipal boundary who may be so circumstanced that they can adopt the principles I have advocated. No! we must all be tarred with the same brush, and no quarter is given to those who refuse to allow the municipality to be put to the trouble and expense of robbing them of stuff which they find invaluable on their own land. In Hampshire I have spent a considerable sum of money in freeing the river from some pollution and saving trouble to the town. Incidentally, I have improved the value of a house, and, of course, the rates of that house have been raised. Such a fact is a most effectual check upon the vast majority of those who might wish to imitate what they may approve of in principle, and I feel assured that no real advance in sanitation will be made until there is an equitable adjustment of sanitary rates and we have the right, if we desire it, to pay for water by meter. That water should be paid for according to rateable value, and that the rating authority and the water authority should be identical, seems to me to be an arrangement which the ratepayer will possibly find irksome. The greatest of sanitary troubles in the present day is overcrowding, and this trouble is greatly fostered by our methods of sanitation. And yet we find responsible persons suggesting that open spaces should be taxed at 'site value,' while at the same time they are willing to spend any amount of millions in bringing water from Wales because they think that eventually their dangerously dense population will have a density twice as great. We shall some day recognise the futility of fighting against Nature. It is the engineer's business to overcome natural obstacles, and we of the medical profession cannot but have the greatest admiration for the many distinguished members of that sister profession which, by its skill and daring, has in countless ways assisted the development of our commerce and manufactures. They have, indeed, 'expelled Nature with a pitchfork,' but it behoves us to remember the rest of the quotation. We must distinguish also between brilliancy of achievement and the end attained. We all of us admire the brilliant men who made the Thames Tunnel, built the 'Great Eastern' steamship, and gave us the luxury of the broad-gauge railway; but it is doubtful if the original shareholders in those enterprises would participate in our enthusiasm. Money will accomplish nearly anything in the engineering way, and it is not the engineer's business to consider the financial side of the question. I have always had a shrewd suspicion that Archimedes was possibly less admired by the Syracusan ratepayer than by the rest of the world, and I have often pondered whether, had he lived in these days, and had made his famous request of δὸς ποῦ στῶ, the Local Government Board would have sanctioned the issuing of a Syracusan 3 per cent. stock to provide the fulcrum for which he asked.

I frequently meet friends who say, 'I've been reading that article of yours about the earth,' and so forth, and then, after patting one on the back and being charmingly complimentary, they generally end by asserting that, after all, the convenience of the water-closet more than counteracts its disadvantages. The fascinations of this winsome apparatus seem unconquerable, and one is bound to confess that—provided the machine be of a good pattern and well made; provided the plumber who sets it has knowledge and a conscience; provided those who use it do not try its constitution with brickbats and old boots; provided there is not a frost; and provided there is not a drought—it does sweep out of the Cockney's house material of the use of which he is ignorant, and for which he has no market. All the difficulties and dangers of the water-closet are on the far side of the trap, and do not trouble the householder. I feel inclined to paraphrase the words which King Lear used to something equally fascinating and, as he found, equally treacherous:—