LONDON FOGS

BY

THE HON. R.RUSSELL, F.M.S.

LONDON
EDWARD STANFORD, 55, CHARING CROSS, S.W.
1880

[-3-]

LONDON FOGS.

IT may be a wise doctrine, that no ancient and long-tolerated institution deserves to be condemned without a fair inquiry into the evidence for and against its existence. A London fog, like most disagreeable things and persons, may have its merits, and, doubtless, also its firm partisans, who would be prepared to defend it in a general way before a Royal Commission as a beneficial visitation. But the proofs of its utility, if they exist, must be brought to light, and as yet we have had none. It may be upheld as a nebulous and mysterious witticism, a gigantic piece of national humour, an enormous practical joke, and we cannot dispute the plea that it may be a source of amusement to its passing acquaintance. But those who know it well have had enough of it. It has hitherto been spared, because, like other evils of greater magnitude, its ill effects have not been very startling and sudden, and it was hard to believe that so harmless-looking and quiet a thing could do much mischief. The unseen and little-[-4-]noticed causes of death and disease, however, are by far the most fatal. The small germ of typhoid or drain fever slays its thousands every year; but this fact attracts less general attention than the drowning of five hundred by a collision or by a flood. Yet of these the first is the most easily preventable evil. So we have been content to pour the refuse from our domestic fires into the open air, and leave the work of scavenging to unaided natural forces; to disregard "matter in the wrong place," so long as it has not killed its hundreds or thousands at a time, and have tolerated something like suffocation, so long as it performed its work slowly, made no unseemly disturbance, and took care not to demand its hecatombs very suddenly and dramatically. And smoke in London has continued probably for many years to shorten the lives of thousands, but only lately has the sudden, palpable rise of the death-rate in an unusually dense and prolonged fog attracted much attention to the depredations of this quiet and despised destroyer.
    Moreover, these fogs, and the smoke which is perpetually present in the London atmosphere, affect property more seriously than many great fires or floods, laying year by year a not inconsiderable tax on the mass of humanity thus "simmering in their own gravy" or pea-soup; but the tax being indirect, is not murmured against. The fact that, for a great city, London [-5-] is on the whole a healthy place, and that many people live there as well as elsewhere, does not prove that it might not, with a purer air, attain a still higher degree of salubrity. Every year its thick, heavy, winter blanket grows thicker, and its summer garments more resemble those which were formerly sufficient for the cold season. This is only to be expected while houses and streets develop at their present rate in all directions. The opinion is strengthening that something must be done, and in England a well-founded opinion always ripens into action.
    A London fog is a complex phenomenon, greatly differing from a country fog, and since it does not depend altogether on the natural action of temperature, winds, and vapour, may be dealt with, qua London fog, as a removable evil. Our subject may be divided into three parts: 1. The characteristics of London fog and haze, especially in relation to weather. 2. The damage to health and property by smoke and soot in the air. 3. The means of prevention.
    1. The following are the chief distinctions between a London and a country fog.
    A country fog is white, without smell (unless perhaps a slight odour of ozone), and not disagreeable to breathe. It seldom thickens after the first hour after sunrise. It is pure condensed vapour,* [-* A small quantity of carbonic acid gas, &c., may be held in solution.-]  [-6-] and therefore clean. The sun appears perfectly white when seen through it.
    A London fog is brown, reddish-yellow, or greenish, darkens more than a white fog, has a smoky, or sulphurous smell, is often somewhat dryer than a country fog, and produces, when thick, a choking sensation. Instead of diminishing while the sun rises higher, it often increases in density, and some of the most lowering London fogs occur about midday or late in the afternoon. Sometimes the brown masses rise and interpose a thick curtain at a considerable elevation between earth and sky. A white cloth spread out on the ground rapidly turns dirty, and particles of soot attach themselves to every exposed object.
    Haziness, if not fog, prevails in London on nearly every day in the year. London haze is quite a different thing from that which occurs naturally in the country, though at times very similar to it in appearance. It is absent only during part of the night and early morning. Every one who has seen the metropolis in the small hours of a fine morning knows the totally changed and unfamiliar appearance of the town when nothing interrupts the vision. On fine, hot, breezy Sundays in summer, when factories are stopped and fires not so much used for cooking, the clearness is so unusual that prominent objects such as St. Paul's Cathedral and the Albert Hall may be seen from distant suburbs. In the daytime, a sightseer on [-7-] Primrose Hill or Hampstead Heath, even if he be a poet, will be fortunate if more than a small number of "distant spires" reveals itself to his gaze.
    Smoke-haze is bluish, dirty-grey, or brown in colour, may be smelt if thick, and renders the outlines of clouds murky and ill-defined. The last distinction is the best, and if clouds are overhead, the peculiar grey dirtiness of smoke blurring their edges is almost unmistakable. The dweller in the distant suburbs only rejoices in these town-fogs and town-hazes during the prevalence of certain winds or currents. Generally he may assume coal- smoke to be present when unusual darkness of a peculiar yellowish or brown tint prevails. This darkness is caused by the minute particles of carbon, a substance which, unlike the water particles which compose a pure fog, is incapable of reflecting and transmitting light. He will recognise smoke also in the yellow murky clouds which occasionally pass over his head, with a clear air below, carried by a different current from that prevailing on the ground. In the south-western suburbs, a change from westerly to a north-east wind is commonly· preceded by a smokiness sufficient to conceal distant objects. Many people are apt to mistake the darkness caused by banks of smoke resting above them for the effect of thunder clouds, or naturally gloomy weather, and one frequently hears remarks upon the thundery appearance of the sky, and [-8-] predictions of a storm, when the weather simply happens to be calm enough to allow the refuse of our fires to accumulate and drift slowly above our heads. These dense banks of smoke sometimes pass over a great extent of country, and produce a gloomy appearance at distances of thirty, forty, and even fifty miles or more from the metropolis, for smoke is far less changeful and less easily dissipated than clouds. These dark murky days, which are bright and fine in the windward districts and in the far country, frequently occur in the suburbs, and with especial persistence during fine, calm, and cold winter weather. A London fog may be very unequally distributed, and may even be dense in one quarter while the sun shines brightly in another. It may move slowly in masses, so that at any one spot we have alternations of light and obscurity. This movement and aggregation depends upon the feeble circulating and variable currents which are most favourable to the development and continuance of a thick fog, and upon the tendency of condensed vapour and all small particles to aggregate in defined patches wherever there is sufficient movement. Generally, with a steady easterly wind the West End will be most obscured, with a steady west wind the East End, and similarly with other directions, in suitable fog-conditions. But suppose a dense black fog prevails at the West End with a light westerly wind, we must not call this an ex-[-9-]ception to the rule, until we have ascertained that this westerly wind blows also at the East End, and that there is no east wind overlying the west wind at a moderate altitude above the ground. In fact, we should probably find such a conjunction to exist.
    In regard to steady breezes blowing over the whole town, we may calculate for our own locality, with perfect accuracy, which wind will bring us the largest quantity of mist, by finding on a map in which direction the greatest length of chimneys would have to be traversed. Thus, at Westbourne Grove, an east wind would have passed over more than seven miles of houses continuously, and at Hammersniith, an easterly breeze blowing from the direction of the East India Docks would bring the smoke of ten miles of houses; at Holloway, a southerly breeze would be loaded with the pollution of seven miles. The opposite winds at each of these places would generally be the clearest, but it must be remembered that at no great elevation winds contrary to those on the earth occasionally prevail. In the more distant suburbs the same rule will hold good, though the fog or murkiness will be less thick and dark. Thus at Southgate and Barnet southerly, and at Romford southwesterly winds are scarcely ever clear for distant views. At Richmond and Kingston N.E., at Windsor E. and E.N.E., at Sydenham N.W., at Woolwich and Greenwich W., and at Harrow S.E,, is the direction of least transparency. We [-10-] may take a much wider circle without error, for smoke can neither be dissolved nor absorbed, and can only be got rid of by being deposited with moisture or rain, by being caught by the leaves of trees, etc., or by falling to the earth by its own specific gravity, and it remains visible until very highly diluted. In dry weather it generally rises high into the atmosphere, and is carried away at a great elevation. The distance to which smoke may travel without reaching the ground is quite indefinite, for after the eruption of a volcano even masses of fine ashes have been known to have been carried many hundred miles before descending to the surface of the earth. Dust has been collected on board ship at enormous distances from the continent to which it belonged, as indicated by the microscope. Thus, from analogous cases, it may be inferred that coal- smoke may be carried far and wide by the currents of the air, until it has become so excessively diluted as to be invisible. And we cannot doubt that some of the slight mists observed in the remote country in dry weather are derived from London and other large towns. At Richmond, nine miles from Piccadilly Circus, the effect of smoke upon the climate has been strongly marked. The climate of Richmond has indeed altered much for the worse during the last fifteen years. London fog and London gloom reach the district more frequently, and the distant views from Richmond [-11-] Hill are far oftener hidden by ugly mists than in former years. The large increase of Kingston-upon-Thames, Twickenharn, Teddington, and Richmond itself', has something to do with this pollution of the air westward, but the thousands of houses which have grown up on the western and south-western outskirts of the capital probably contribute a more considerable increment. To this enormous extension westward may also be attributed the increase in the frequency of fogs in the districts of Belgravia and Mayfair, for they now suffer from the contaminations of the west as well as of the east, and the fresh air of the country is intercepted on all sides.
    It is certain that private houses, and not factories, are chiefly responsible ; for some of the very worst fogs have occurred on Sundays, and Christmas Day, 1879, was nearly dark.
    In winter more than a million chimneys breathe forth simultaneously smoke, soot, sulphurous acid, vapour of water, and carbonic acid gas, and the whole town fumes like a vast crater, at the bottom of which its unhappy citizens must creep and live as best they can. if a moderate breeze blows, the products of combustion are removed to other parts of the atmosphere as fast as they are formed, and no dark fog can exist. But when the air is nearly or completely calm, the case is different. In winter the earth does not become sufficiently warmed by the sun to cause the air near its surface to rise, and [-12-] the lowest atmospheric strata gain little heat even in the open country. When a substance not susceptible of evaporation obscures the low-lying fog- cloud even before sunrise, the cloud cannot gain warmth sufficient to dissipate it if the conditions which produced the fog are maintained. These conditions are, usually, the mixture of opposite winds and a clear sky above the fog-bank. Of what does a London fog consist? First, of a multitude of watery particles, such as make up a common fog; secondly, of a vast number of flakes of soot of various sizes; thirdly, of smoke proper, or minute particles of carbon; and fourthly, possibly, of smoke or carbon particles joined to the watery particles of the fog. Smoke and soot are not soluble or easily mixed in water, and it is therefore not likely that the particles of smoke actually dissolve in the water particles. There is repulsion, not adhesion, between the two substances, and a London fog is well accounted for by the accumulation of smoke alone, which any one can see to be dense and persistent enough when it comes straight from the grate into his room, where there is no condensed vapour of water. The fact is, that the white fog- cloud or stratus prevents the ascent and dissipation of the smoke which is ejected into it in the morning, and then the accumulated smoke mass in its turn resists the rays of the sun, and so prevents the evaporation of the natural fog. It is quite unnecessary that there should be any natural fog in [-13-] order to produce great darkness in London. The fog is a concurrent circumstance generally present. But when the air is cairn and in a condition of stable equilibrium, the lowest strata being the heaviest in spite of sunshine, and striated horizontally, the smoke alone may form a pall over London when the air is otherwise perfectly clear. . This phenomenon is most apt to happen on a fine still morning, when the air is dry and heavy and the temperature low or falling. Any one who has watched from the shore the smoke of steamers passing through the English Channel on a calm day knows that the hand of smoke left behind them will often lie for hours together nearly in the same position, like a long, low cloud. Now, if this band remains undissipated in clear weather, it is likely to be still more persistent in a fog, when the air clings to the earth's surface in a horizontal stratum. And when the quantity of smoke is many hundred times greater, and, unlike the smoke of a steamer, continues to be evolved into the same superjacent portion of air, the resulting smoke-bank must be very much thicker. Similarly, on a calm, clear evening the smoke of a cottage in the country descends and arranges itself in a horizontal layer above an adjacent meadow, where radiation is rapidly proceeding, and not seldom, in the early morning,
        "The sun, new risen,
        Looks through the horizontal misty air,
        Shorn of his beams."
    [-14-] We should thus expect to find that the darkness and severity of yellow fogs are in the proportion of the size of towns, their conditions being similar with regard to the use of coal. And this is strictly the case. Liverpool, Birmingham, Manchester, and Glasgow, consume large quantities of coal, and their fogs resemble those of London. Edinburgh, Brighton, Dundee, and Dublin, consume much less, and escape with a very moderate degree of darkness in moist still weather, and a certain amount of mist. The cloud of smoke at Brighton offers a good opportunity for observation in calm cold weather. It is sometimes, though rarely, sufficient almost to exclude sunshine from the town. In still smaller places only a slight mist hangs about; and in the western towns, where coal from the northern pits is little used, the atmosphere is much clearer. In Paris, since the more general employment of coal as fuel, yellow fogs have occurred resembling those of our own capital. Lyons is peculiarly subject from its situation at the junction of two large rivers, to the stagnation of atmosphere which favours the production of fogs, and these are of course tinged with the smoke of its numerous factories. Wolverhampton, Birmingham, and the black country generally, evolve an amount of smoke which not unfrequently plunges the traveller from north or south, where he has enjoyed bright sunshine, suddenly into a fuliginous gloom almost equal to that of night. Middlesborough  [-15-] and Cleveland also succeed in almost excluding daylight from the district. In the South Wales manufacturing districts, so long as native coal only is used, there is a complete absence of dark fogs, and vegetation thrives on the very tips surrounding the coal-pits.
    Let us now glance for a moment at the behaviour of a London fog under different circumstances. If a natural fog with a clear sky prevails in the early morning in the London district, it will remain white until the smoke from innumerable freshly- lighted fires loads it with smoke and soot. If the season be early autumn or spring, and temperature not inclined to fall, the fog will probably be dispersed by the heat of the sun and ascending currents before midday. If the sky be cloudy, and the air remain still and cold, the fog or darkness will probably not disperse during the day. In winter the fog remains in any case to some extent, provided the air be still, temperature keeping low. If the sky be cloudy, without fog, and a calm prevails to an altitude, the smoke will rise and remain at the height of the cloudy pall or somewhat lower, causing great darkness, and this may occur either in winter or summer, when the temperature is below the average of the season. With a clear sky it will commonly not rise so high. Thus on June 10, 1880, the Ascot Cup Day, while the weather was exceedingly fine outside London and its immediate neighbourhood, and rather cold for [-16-] the season, a dense mist and darkness covered the city during the morning, rendering gaslight necessary.
    Fogs caused by the mixture of currents and the advent of a south-west wind after a cold period with northerly winds are commonly wet, and, unlike dry fogs, reach to a greater height. Such was the fog of October 27, 1880, caused by the advance of a great cyclone, of which the centre passed over the Midlands. Warm south-west winds advanced over southern England, and replaced the cold easterly winds after producing a very wet fog, which lasted a few hours. What happens when a gentle steady breeze or air blows from one direction in a cold and cloudy atmosphere? The smoke occupies that portion of air lying between the earth and the clouds, not rising higher than the clouds, and stalks across the country, borne by the prevailing current; leeward of London a black fall of soot and no little gloom continues over a large tract of country, sometimes for many days. This gloom or smokiness spreads slowly out in the shape of a fan as it proceeds, owing to diffusion and small currents, and of course diminishes in intensity. Thus, if originally, in London, it were seven miles broad, it would by the time it reached Windsor, extend over a breadth of fifteen or twenty miles. Richmond, a little over nine miles from Charing Cross, is not distant enough to escape a very considerable amount of gloom and fog brought [-17-] by the north-east wind, and when the wind blows gently from that quarter in cold winter weather, it is sometimes too dark, several mornings in succession, to read without candlelight. Occasionally the morning opens brightly, and between eight and ten o'clock the smoke-cloud arrives. When this wind blows after a fall of snow, the snow rapidly becomes blackened and covered with soot.
    Four or five years ago, in these circumstances, I counted one hundred and six particles of soot on a square inch of snow in Richmond Park after two days of N.E. wind. There had been ice on the large ponds, and after it had melted, the soot which had fallen upon it was driven along the surface of the water until it came to shore in a thick black scum. Indeed, after a period of dry N.E. wind, the leaves of the trees and the grass leave a black mark of soot on everything which touches them. When a slight change in the direction of the wind occurs, the gloom disappears, and may be seen obscuring the country to south or north, according to the direction of the shift. On Sunday, October 24th, the sky was cloudless, with a slight breeze from W.N.W., and the morning broke without fog or mist at Richmond. Between 9 and 10 A.M., however, a thick mist covered the country, dimming the sun's rays, and the wind had evidently changed to N.E., or else a N.E. wind was blowing at an altitude. On taking an observation, thick masses of smoke were seen to be [-18-] passing overhead from N.E., while the wind below remained westerly. Later in the morning the upper wind changed to about N., and the smoke- clouds were driven in a southerly direction, obscuring the distant sky as far as the eye could reach. Thus, on cloudless days in spring, the southern extremity of Richmond Park sometimes lies in bright sunshine, while the northern edge, two miles distant, is only dimly illuminated by the enfeebled rays struggling through brown masses of smoke wafted overhead. In summer, the veil thus interposed between sun and earth is, of course, much thinner. But, nevertheless, it robs many a summer day of much of its beauty. Last August, during a fortnight of north-easterly wind with fine bright weather, which was clear north, south, and east of London, the landscape at Richmond was continuously enveloped in mist during the daytime. On fine summer days, when the air is perfectly clear, the metropolis is invariably seen, from a distant eminence, to be covered with a dirty haze, which hides the greater part of the town from view, and often extends to a great altitude. One day, when the transparency was unusual, I observed that the few small cumulus clouds which passed over the town each seemed to draw upwards a dark column of smoky haze. When in winter the air has been absolutely calm a kind of circulation has sometimes appeared to take place, which is not surprising when we remember that, in [-19-] winter, the temperature of London is between one and two degrees higher than that of the neighbourhood, and that more than 50,000 tons of heated carbonic acid, and a volume of heated aqueous vapour weighing about 18,000 tons, occupying several million cubic yards, are daily projected into the atmosphere above the city. This apparent circulation occurs with a high barometer, and seems to imitate on a small scale the supposed movement of a cyclone, the smoke ascending in the centre and descending somewhat at the circumference.
    The situation of London is favourable to the production of natural fogs. Two conditions give rise to fogs in England ; either the clashing and mixture of two winds, or the contact of moisture- laden air with the colder surface of the earth. Now, London is so placed that it happens frequently to be the scene of the prolonged encounter of north-east and south-west winds. When areas of low pressure exist over the centre or south of France, and somewhere to the north of Ireland or Scotland, gradients for these two winds respectively may be produced in the south of England. Moreover, centres of weak cyclones are apt to stick about the English lakes, and towards the centre of France, and cyclones which have travelled some distance across the Eastern Atlantic, to slacken their progress when they reach Western Europe. In fine weather, also, when atmospheric movements are [-20-] feeble and variable, the Thames affords an easy passage for light breezes from the east, and these are arrested by south-westerly currents which have spent most of their energy in the English Channel. Fogs rarely occur with a low barometer, when the atmosphere is in unstable equilibrium. Areas of high pressure, or anticyclones, have a tendency in certain seasons to stick over England, and fogs are most common during the prevalence of "radiation weather," when the earth loses most rapidly at night the heat very readily gained in the hours of sunshine. The position of London may perhaps be compared not inappropriately to that of Hyde Park Corner, which is notorious as being one of the spots where fogs are almost invariably at their densest. At Hyde Park Corner currents from south and east meet another of different temperature pouring through this easiest outlet from Hyde Park. One evening last February, between 6 and 7 P.M., the overflow from Hyde Park rolled down Grosvenor Place in a billowy stream like water, while elsewhere the air was calm. So the lower Thames Valley affords an approach for the easterly wind to make its inroads into the moist equatorial current. Fogs are prevalent in estuaries owing to the difference of radiation from land and water producing currents of air of different temperature, and the cold air from the land passing over water at a higher temperature where the air is saturated with moisture, or the warmer air from the estuary coming in contact with the [-21-] cold strata on land or the land itself. In "radiation weather," or during the continuance of high barometric pressure, when the air is dry and permits radiation more freely into space, all inland stations suffer from fog, from the contact of the cold earth with the heaviest atmospheric strata, which, owing to their weight, retain their position. In the open country the sun often dissolves these fogs, and they only reappear at night. But, owing to the blockading power of London smoke, the very finest winter weather in the country is generally the very worst in London. Except when a wind blows within a moderate height from the ground, London knows nothing of the "frosty but kindly winter days.
    The following table shows the days on which fog occurred at the Botanic Gardens, Regent's Park, last winter, and the height of the barometer at 9 A.M. It will be seen that atmospheric pressure  was unusually high during the fogs.

    [-22-] The fog of the middle of December, 1873, was one of the thickest and most persistent of this century, and deserves to be noticed in some detail; not because it differed from the ordinary London fog, except in intensity, but because the character and effects of these fogs are unusually conspicuous in this instance. I was residing at Richmond Park at the time, but, having occasion to go daily to London, thought it worth while to pass through several districts of the town for the purpose of making observations on this remarkable fog. After about a week of cloudy, misty, and quiet weather, on the night of December 8-9, a hard frost came on, with a scarcely perceptible air from W. The 9th was a very fine day in the country and at the western suburbs, but in London there was a dense black fog all day, and many accidents occurred on the river and in the streets. On December 10 the frost continued. At 8 A.M. the thermometer was 22. The calm continued, only a very light air from W. prevailing near the ground, but higher up from N.E. The smoke of London was drifting over Richmond from the N.E. The barometer remained very high. In London, the weather was the same as that of the day before, and many of the fat cattle exhibited at the Great Show at Islington died of suffocation. It was not possible during a great part of the day to see across a narrow street, and in the evening a choking sensation was felt in breathing. On the 11th, [-23-] the barometer stood at 30.62, the thermometer at 22. At Richmond the weather was fine, with mist, a dead calm, then a lower current from W. and S.W., and cirro-cumulus clouds from E.N.E. Foggy in London. On the 12th, barometer steady, thermometer about 32; a thick and damp ground-haze. Not so bad in London. Dead calm, but local currents as follows :-Vauxhall, S.E.; Ludgate Hill, S.E.; Camden Town, N.W.; Richmond, W. Cirro-cumulus were still moving from E. On the 13th, a ground-haze at Richmond, cloudy, and dead calm. No very thick fog in West London. Barometer still about 30.64. On the 14th, very slight drizzle in London about 9 A.M. Dead calm. Current N.W. at Belgrave Square; S.E. in City and at Shoreditch at 10 A.M. Dark yellow fog, rapidly thickening northwards from the City, till at Haggerston pitch-black darkness at 10.15 A.M., the lower air being tolerably clear. About a mile of this darkness like that of night then gradually lighter towards the west, and at Camden Town fair, at Jampstead pretty clear and cloudy, clouds hanging at an elevation of about 350 feet above the sea. At all stations north and west of Haggerston (on the North London line) a N.W. current. In the afternoon a gentle breeze from W.N.W. Thus ended this long period of calm. The deaths exceeded the weekly average by about 700.
    We have, in the above instance, a concurrence [-24-] of several conditions favourable to the formation of the worst London fogs, namely :- 1. Perfect calm. 2. High atmospheric pressure, and a dry light air. 3. Great cold. 4. A conflict of currents. It is obvious that great cold favours the development of a dark London fog, for this reason, besides others, that a much larger quantity of coal than usual is burned.
    The fog of Christmas Day, 1879, was attended with nocturnal darkness in London. In the country it was remarkably thick throughout the day.
    Some of the great fogs of the end of January and beginning of February, 1880, were uncommon in their character and development. On the 27th of January there was a sudden great increase in the intensity of the frost, almost absolute calm prevailed, and the easterly current gave way on the ground to a westerly air, with which it became intimately mixed. The east wind apparently continued at a moderate elevation. In many parts of London the fog was exceedingly dark, being mixed with a great volume of smoke, and the sun was invisible. At Hammersmith, at midday, the sun was just visible, at Richmond shining dimly, and at Willesden very brightly. The fog was not inconveniently thick outside London till the evening, when it greatly increased in density. At Richmond, at 2.45 P.M., the thermometer stood at 22, an extremely low temperature. More or less fog occurred here and there on the following days, and [-25-] the sky remained clear above it. On the 30th and 31st an exceedingly light lower current from the south moved over southern England, greatly augmenting the temperature. Radiation, however, was not arrested by clouds, and the ground being chilled to a temperature much below the freezing- point by the previous severe frosts, did not thaw even when the thermometer stood at 45 in the open air. Thus, in certain localities, especially those least exposed to sunshine, very dense clouds were formed upon the ground by the reduction of the temperature of this slow warm current below the dew-point. On the 31st, at 10 A.M., a ground fog of extraordinary density, little discoloured by smoke, lay over parts of the south-western district of London. I measured the distance at which objects became visible, and found it to be four and a half yards. In some places the fog did not extend as high as the tops of the houses, and the smoke thus escaped into the upper air. In central London, great darkness accompanied the fog during the morning. This fog differed from most others in being entirely due to the chilling of a single atmospheric current by contact with the earth; and for this reason it extended in its intensity only a few feet above the ground. The day was extremely fine in some of the suburbs. In the evening, with a rapid fall of temperature, the fog returned and caused the greatest difficulty to locomotion. On the 1st of February the atmosphere was less foggy [-26-] in most districts, but again became almost impenetrable for traffic in the early morning of the 2nd. On the 4th the fog was again exceedingly thick. The fog had thus lasted eight days, on and off, with very great intensity. They were remarkable for their local character, the shady side of a square being several times plunged in a dense mist, while the opposite side rejoiced in sunshine; one end of Piccadilly in thick darkness, while the other remained bright and clear. The following figures indicate the effect of these thick smoky fogs on health:

The death-rate thus increased from 27.1 for the week ending January 24 to 48.1 for the week ending February 7, which was the period of thickest fog. The death-rate for this last week in nineteen provincial towns was 26.3. The terrible effect of the fogs continued to show itself in the death-rate for the week ending February 14 as follows
    Total .. .. .. 2495 .. Above Average 730
    From Respiratory Diseases 1020 .. Above average  551
In Richmond and Kingston together, the deaths, [-27-] which had been 30 in the week ending January 10, rose to 42 in that ending February 7; in Stratford (east end of London), they rose from 13 to 24, but at Croydon only from 35 to 36. The death-rate at Haggerston, in East London, was about doubled, as it had also been in the foggy week of December 1873. In the week ending February 7, the deaths from whooping-cough in London were unprecedentedly numerous, namely, 248; and from bronchitis, 1223. Fevers seemed to be little affected. The excess of deaths in London during the three weeks was 2994, and of these probably at least 2000 may be ascribed to the character of the fog alone, and not to the cold. In the foggy week of December 1873, the deaths were more than 700 above the average. Of these probably at least 500 were due to the character of the fog. Such are the results, more fatal than the slaughter of many a great battle, of a want of carefulness in preventing smoke in our domestic fires. It is not only the prize cattle at Islington which perish, but a multitude of human beings, strong and weak. In the fbgs of January and February, not only the aged and feeble, and persons affected with bronchitis and lung disease, but the strongest and healthiest, were literally choked to death. Of three young men who were out together in the evening of the worst fog, two immediately fell ill from its effects, and died, and the third had a sharp attack of illness. Thousands of people were thrown so much out [-28-] of health that they did not recover for some weeks. In an article of the 'British Medical Journal,' we find the following observations on the mortality of this period :-"The annual death-rate for the week was 48.1 per 1000 of the estimated population; whereas in the nineteen provincial towns the rate did not exceed 26.3 per 1000. The recent cold was fully as severe in many other parts of the country as in London; it is therefore fair to assume that the exceptionally excessive fatality in the metropolis was due rather to the fog, which was local, than to the cold, which was general." The increase of mortality on that of the preceding week, which was also high, was 54 per cent. for the whole of London, 32 per cent. in the west groups of districts, and 83 per cent. in the eastern districts. The article then proceeds: "It is smoke that makes London fogs so mischievous; and bearing in mind the disaster of last week, it is worth inquiring whether something cannot be done to mitigate the main cause of this remarkable mortality. Now, it is certain that much can be done both to remove the special cause of excessive mortality in London fogs, and to increase the general wholesomeness of the London atmosphere, with little trouble, and considerable pecuniary gain to the community. The death-rate during a few days of dense fog palpably mounts to an extraordinary degree, but every year we have a large number of ordinary London fogs [-29-] of less density, which, lasting as they commonly do only one or two days, fail to affect the death-rate sufficiently to be noted as the cause of any small increase above the average which may occur. It would be idle to doubt that bronchitis and lung- diseases are dangerously heightened by moderately thick smoke-fogs, when the thickest fogs produce so great a mortality from those diseases. An excess of 600 deaths in the week elicits comment, but an excess of 60 from this cause, occurring perhaps when the rate is below the average, would hardly be noticed. Besides, fatal effects occur in many cases long after the actual cause of illness has ceased, and these escape notice.
    We may infer that numerous deaths occur in the course of the year from smoke-fogs, not unusually thick, producing or increasing diseases of the lungs. Besides these cases, we must reckon a large annual loss of life from the perpetual presence in the London atmosphere of smoke and soot, blocking up the air passages and irritating the mucous membrane so as to lead to consumption, lowering the vital energy, depressing the system both by the impurity of the air breathed and by the deprivation of light, for these influences tell heavily on many constitutions, especially those which happen to be in a weak state of health, as those recovering from fever.
    Dr. Angus Smith gives the following as the [-30-] percentage of carbonic acid found in air at different places:-

Mean of the country  .0341 per cent.
Two miles from Clapham Junction .0345
Middle of Hyde Park .036
Bethnal Green Road .049
Street in Manchester .040
Same in Fogs .067

    Here we have the rather surprising result that in a fog the impurity of the air in a town is increased by more than half its normal impurity. It is a proof that the carbonaceous products of combustion do not readily disperse in a fog, but cling to the neighbourhood of the ground. The air of London is not only impure, but deprived of ozone, and on this account is not favourable to convalescents. The very frequent exclusion of sunshine in cold weather by smoke, and the cold, damp fogs and mists retained by it in the town, cause an increase in the use of spirituous liquors, which again lead to disease, misery, and death. The winter gloom of London is very unfavourable to sobriety. Owing to the prevalence of westerly winds the eastern portion of the town suffers more from smoke and fog than the western, and from this and other reasons its inhabitants present an unhealthy appearance altogether unlike that of the country population. The evil effects of smoke upon health may be roughly classed as follows: Actual suffocation of healthy persons; aggravation of lung diseases, bronchitis, [-31-] and nervous disorders; prostration of convalescents and others from want of fresh air; effects similar to those produced more conspicuously by dust in grinding mills, factories of textile fabrics, etc., by the constant presence of small solid particles in the air, weakening the system and shortening life; effects upon the mind and spirits, resulting frequently in a resort to alcoholic drinks, producing disease; damage to eyesight by want of light and use of gas; accidents by railway, road, and river.
    Beyond these bodily hurts, the presence of an overshadowing cloud of smoke produces moral evils which at least deserve some consideration. The population which has hitherto made no serious effort to rid itself of the pollution with which it contaminates the vital breath of heaven suffers seriously for its neglect. They lose, in the first place, that glorious and almost universal privilege of looking upon the clear azure above them, a clear-setting sun or clear-rising moon, the magnificent cloud-castles of summer, the delicate hues and forms of clouds, and the crisp brilliancy of every fine winter morning. They lose, too, all distant prospects, urban or rural, and the pleasant variations of cloud-shadows which delight us in the views of great continental cities, which are not blurred or blotted out by smoke. These things are sermons from nature which humanity has need of. London is indeed hideous to look at, but would be [-32-] less hideous without its smoke. What is the meaning of the expression, "Going to the country for fresh air," but that Londoners, of whom there are three millions, spend the greater part of their existence in foul air, surely a vast deprivation of a natural blessing? Many a life has been saved by timely removal to country pursuits. It is no joke to those who cannot leave their occupation. Air is to man more than water is to fish; he not only moves in it, but breathes it and lives upon it, and contaminated air deprived of its ozone fails duly to refresh him. If we examine the conditions of various trades, we find that those which are most unwholesome to the body tend also to crush out the wholesome buoyancy of the mind. Even the poorest people in the English country districts have, on the whole, an appearance of contentment and good health and spirits, but among the poor who are natives of London the prevailing expression is one of pallor, discontent, and ill-health, especially among women. Smoke and bad air by no means effect all this; they only contribute to it, with strong drink, overwork, and artificial habits. Natural gaiety can hardly be expected in courts and alleys steeped in grime. Flowers from the country, the spring green of the black funereal trees of parks and squares, the health and spirits of the people, soon fade to one sickly hue. The one thing for which, more than any other, the poor of London express envy of the rich is the power of [-33-] going at any time "to the country." Schools are allowed one day in the year for "fresh air" in some suburban fields, and it is said that this one day is remembered like a happy dream by those who pass the other three hundred and sixty-four in a wilderness of bricks and mud. Certainly, existence in the perpetual vapours, often stagnant, of a vast and dismal city can hardly be called life, and the poorest countryman fares better and lives longer than the average born citizen.
    Another sad effect of smoke is the hopeless way in which it defeats attempts at cleanliness and neatness among even the most scrupulous of the poor. Wives of labouring men coming from the country find the task of keeping their houses clean too hard for them, and give it up in despair. A forced neglect thus eats into the domestic happiness, and disheartens the spirit of the best of them. Then there is the worry and trouble of smoky chimneys, chimney-sweeping, window-cleaning, renewing and cleaning dirty furniture, dress, &c.; extra washing, and the annoyance of having to keep windows closed for fear of smoke or soot entering, and of window-panes covered with a thick film of dirt. There is no reason why London, if freed from its smoke, should not wear as bright and cheerful an aspect as Paris or Brussels. It would be worth while to paint or whitewash its shabby brick walls, and the streets would soon be enlivened with colours, if our own capital were in general as [-34-] clear as it is at 5 o'clock on a summer morning, its people would find that a load of which they were unconscious had been removed, and there would be less talk of weak nerves and bad circulation. If the air could be cleared of smoke, trees and flowers which now perish would thrive; the whole town might be sprinkled with gardens and shrubberies, not black and hideous to look upon; and the streets planted with various trees.
    We now come to the question of damage to materials done by smoke, and the financial portion of our subject. The outlay rendered necessary by our unnecessary custom of polluting the atmosphere with unburnt fuel is enormous. Almost everything suffers, from granite quays and columns and the stony surface of the Houses of Parliament to the most delicate satins and silks and coloured fabrics of all kinds. The soot and carbon particles deposited on the stone, being charged with sulphurous and carbonic acid, eat away its substance and make renewals necessary at great cost. The drinking-fountain at the end of Great George Street, Westminster, is an example of the rapid spoiling of works of art. It requires restoration five times as often, at least, as it would need in the country. All monuments, statues, and gilding rapidly lose their brightness and whiteness. Iron rusts far more rapidly than in the country, and other metals quickly oxidise. Galvanized iron and bronze do not endure. In these effects sulphurous and sul-[-35-]phuric acid, resulting from the combustion of coal, are mainly concerned. Mortar swells and crumbles; many expensive textile fabrics can hardly be exposed to the London air without rapid deterioration; many colours will not remain. Pictures gradually become dingy, and require cleaning; and watercolours and frescoes cannot live long unless well protected. Tapestry, and all fine needlework, soon lose their beauty. The outsides and insides of houses painted white frequently require a fresh coat, and ceilings soon grow black if not frequently whitewashed. Books and engravings rapidly become dirty, and require frequent dusting. Sculpture cannot be exposed to the open air without becoming dirty, and even in houses requires cleaning, which wears it down in course of time. The sitting figures, for instance, on the north side of Burlington House might, but for their European garb, be taken for Zulus. The names of streets and railway stations, names of shops and signboards, advertisements at stations, etc., require frequent renovation. Curtains and blinds soon become dingy. All kinds of apparel, if not dark, become discoloured, and the cost of the necessary extra washing of linen amounts to a vast sum. Gas must be used very frequently earlier than it would be required in the country, and sometimes burnt a great part of a day or all day, and some waste also occurs in the extra use of lamps and candles.
    Another extra expense is the additional coal [-36-] used beyond what would be burnt if the cloud of smoke did not frequently exclude sunshine in the finest weather. In winter, the very days on which sunshine is warmest in the country, are the darkest in London. It has been ascertained that the sun shines in London with only two-thirds of the power, on an average, with which it shines in the country. The early part of the night, it is true, is a little less cold than in the country, but this does not make up for the ioss of the sun's rays.
    The proportion of unburnt fuel escaping into the air is worth considering when the total annual consumption of coal in London amounts to about 10,000,000 tons. Dr. Angus Smith considers that in Manchester 1 per cent. is thus lost. I have adopted this estimate for London.
    Our imperfect system of heating brings into use a wonderful variety of extremely ugly and expensive cowls and other contrivances for inducing the smoke to go out instead of into our houses.
    Lastly, a vast number of people prefer to live at a distance from their offices rather than remain permanently in the foul air of the metropolis, and for this removal from smoke they sacrifice, of course, a portion of their income. If the London atmosphere were cleared of its smoke, it would be quite wholesome enough to satisfy a large number of those who now make the tedious double journey, preferring the suburbs mainly on account of its salubrious air. Obviously there would be [-37-] not only a saving in travelling expenses, but an increase in the value of house property in London.
    The cost of all these noxious effects can only be estimated in a very general way, but the following list probably presents no exaggerated view of the annual loss to the people of London

Extra washing (including extra soap used for all purposes). Dr. Arnott's estimate, some years ago, was much higher, namely, £2,500,000 . . . . . . £1,100,000
Dresses, curtains, carpets, and all textile fabrics damaged and renewed . . . . . £200,000
Wall.papers replaced; time and labour . . . . . £50,000
Houses painted inside or outside, say once in 5 years, instead of once in 25 years, and whitewashing ceilings, &c . . . . £100,000
Restoring gilding, metal-work, shop-fronts, names of streets, advertisements, stations, pictures, works of art, monuments, theatres, &c . . . .  £100,000
Slow destruction of stonework, granite, marble, etc., on public and private buildings . . . . . £1,000
Extra chimney-sweeping  . . . . . . £20,000
Window-cleaning of public and private buildings, including station-roofs, etc., time of servants included . . . . . £50,000
Extra gas, candles, and lamps, used  . . . . . £40,000
Escape of 1/100th part of fuel into atmosphere . . . .  £100,000
Depreciation of house property, loss of time by illness caused by fogs, loss of time and money by travelling of persons who would otherwise live in London . . . . . .. Not estimated.
TOTAL . . . . . More than £1,761,000

    It will be observed that the waste of heat by our present uneconomical fireplaces has not been taken into account in the above list.
    We now come to the fourth and last part of our subject, the means of diminishing smoke. Far from being insoluble, the difficulty before us pre-[-38-]sents several points at which it may be successfully attacked, provided public opinion be not favourable to the continuance of the present system, with all its faults. We shall briefly consider, first, improvements in the common domestic fireplace; secondly, improvements in the fuel used; and thirdly, the introduction of new means of heating.
    The old fireplace contained a large grate in a large chimney far back from the room. A large quantity of air was thus drawn into the flue, and a large proportion of the heat radiated did not enter the room. The best modern grates are constructed very differently. Projecting as far as possible into the room, with a small adjustable opening to the flue, solid earthenware bottom and sides, and a large radiating and reflecting surface to the room, with flat shallow bars, they utilize a much greater proportion of heat, and burn very much less fuel, while requiring less attention and retaining the live coal longer. If made up, after the fireplace has become well-heated, with lumps of coal and coal dust on the top, the fire will burn for ten or twelve hours without attention. Since the combustion in these grates is slower and more - perfect, less smoke is evolved than in the old- fashioned grates, and an excellent bright fire may be kept up with cinders, which do not give out smoke. If large enough, they will burn coke, a substance which only smokes when first ignited, and emits a pleasant glow without flame. No im-[-39-]provement in warming appliances deserves higher commendation than that by which fresh air is brought from outside the house through a pipe to a chamber behind the fireplace and warmed before passing into the room. It introduces plenty of fresh air without the cold draught which commonly crosses from the doors and windows to the chimney, and utilizes part of the heat conducted through the sides of the grate. Thus, coal is economized and windows and doors may be made completely air-tight without detriment. Another excellent form of grate utilizes a large surface of radiating fuel by the reduction of the depth of the grate and the increase of its width and height, the flue being made very narrow, with an adjustable damper, so that the fire does not become chilled by an unnecessary draught of air. The bars are made flat and thin. A good fire may be kept up on a simple fire-brick hearth without any grate, admits of expansion to any desired size, and of the addition of coals by merely lifting the fire and placing them underneath. The effect is very pleasing, and a little contrivance prevents much smoke from escaping. This fireplace requires no metalwork, and may be faced with ornamental tiles. Asbestos, heated by gas, produces a moderate glow, can be regulated at pleasure, makes no dust, saves the necessity for a large coal-cellar, and the time of the housemaid, but nearly doubles the coal-fire in cost. It might be improved by utilizing the heat [-40-] of the waste gases which pass up the chimney. At present nearly all domestic fires are fed from the top. To reduce the number of their meals, and thus save trouble, the person in charge heaps on coal largely and recklessly, and thus contributes to the peasoup atmosphere of London, sprinkled with the rejected morsels of unignited pabulum. The cleanest, pleasantest, and most economical method is, undoubtedly, to feed the fire from below. A hollow cylinder below the grate is filled with coal, and a plate at the bottom, capable of being raised by rackwork, pushes fresh coal into the hot embers in any required quantity. It is only necessary to turn a handle to do this, a much more agreeable operation than shovelling coal out of a coalscuttle. Kitchen, as well as other fires, can be supplied in this way. Stoves, like those used in Germany and Belgium, may be introduced with advantage wherever there is no great object in having a cheerful open fire. They are much cheaper in use. Hot-water pipes, connected with the kitchen boiler, or with proper stoves in large houses, maintain a pleasant equable warmth and save fuel. They might be economically employed in warming, from a single boiler, whole rows of houses constructed to receive them. Gas adapts itself easily for cooking and warming, but its high price stands in the way of a very extensive use of it for these as well as lighting purposes.
    A very large diminution in the production of [-41-] smoke would, I believe, be effected by placing a small bounty on the import to London of Welsh or steam coal, and Ruabon coal. Its price per ton is now much below that of the best Wallsend, and about equal to common kitchen coal, so that a reduction of one or two shillings per ton would greatly affect the market in its favour. If, eventually, so much as half the coal used in London should be of this kind, properly called smokeless, a bounty of two shillings per ton would cost less than half the losses annually caused by smoke, arid would return to the consumer's pocket. Steam coal will not burn well without some care in a common open fire, unless mixed with Newcastle coal, but is suitable for stoves with a good draught. Coke makes an excellent fire without same in kitchen grates and others of sufficient size.
    New houses in London are "run up," not built, with very thin walls of porous brick, and through these walls heat is conducted so quickly that in a few hours, when the fires go out, the temperature of the rooms approaches that of the mean daily temperature outside. A middle-sized detached house requires several tons a year more fuel to warm it than would be necessary with walls of a reasonable diameter. As long, however, as builders find thin walls to pay well we cannot look for improvement in this respect. It is a matter worthy of the attention of Building Societies. The Romans were much ahead of us in [-42-] their methods of systematic heating, as may be seen in the remains of their villas in this country. No house ought to be built without free ventilation under the ground floor, and the underground chambers, which should not be used as living rooms, but for storage and lumber, ought to be kept constantly warm and dry by an economical stove. The rooms on the ground floor would thus be warmed by conduction, and the pipe from the stove might either be led through the rooms to the top of the house, or, what would be better still, the warmed air might circulate in a hollow space between an inner and outer wall before escaping to the outer air. This would maintain a pleasant temperature throughout, and prevent any damp from ever penetrating to the inner wall. Much less coal would be burnt in houses thus protected. In every house, the kitchen chimney ought, where possible, to pass through the centre of the house, and to be made of conducting material, so as to utilize some of the heat of the waste gases. In most London houses, however, present arrangements cannot be interfered with.
    Our main object is to determine what means can be devised for arresting and diminishing in London houses, as now constructed, the production of visible smoke, and how these means may be brought into general use.
    What are they? On reviewing them, as above detailed, we may put forward the following suggestions :-1. That coke should be more largely used, [-43-] but especially steam-coal, mixed where necessary with Newcastle coal. That to encourage the demand a small bounty should be put upon steam-coal, and a small tax on other coal of inferior quality. 2. That a small tax should be put upon all new fireplaces of antiquated and uneconomical form, largely wasting heat and polluting the atmosphere. Well-constructed, solid-bottom fireplaces, asbestos fires, gas-stoves, common close stoves, Galton fireplaces, fires fed from below, to be exempt. Fireplaces adapted to burn steam-coal to be exempt. 3. Societies or companies to be formed for letting stoves on hire, so that purchase may be made by instalments over one or two years. A bounty or reward might perhaps be put on proper stoves. 4. A tax on cooking-ranges not constructed to avoid the production of much smoke. 5. Hot- water pipes to be introduced wherever possible on an economical plan. 6. The Metropolitan Board or other authority to purchase the gas-works, in order to supply the town with cheap gas and coke.7. Tile and other manufacturers to be compelled to prevent smoke.
    These seem to be the measures most likely to mitigate, without causing other serious inconvenience, the evils of smoke. It is encouraging to recollect how completely the nuisance of smoke from steamers on the river and from locomotives has been reduced to zero, by the use of steam-coal and proper mechanical contrivances. For some time past I have been convinced that whenever public [-44-] opinion permitted it, the substitution of steam for other coal would be the best way to purify the air of London.
    When in course of time coal becomes dearer, new sources of heating will certainly come into requisition. Nobody can tell how soon new discoveries and inventive skill may make it possible to draw from them. The internal heat of the earth supplies within two or three miles of the surface an inexhaustible reservoir of thermal energy, not indeed at a high potential, but of unequalled steadiness. Is the conductivity of the rocky substance sufficient to replenish the sides of a deep underground system of pipes, according to the drain upon their heat? If so, the earth might be used as the heater for the hot-water apparatus of a whole town, the water introduced returning by its own pressure to the surface, whence it could be pumped into non-conducting reservoirs by steam-engines using the heated water.
    The natural motion of air and water may be reconverted into heat and conveyed as electricity, but the cost of machinery, etc., would not be compensated by the quantity of heat produced; and it is unnecessary at present to look anywhere else but to the coal-fields, for they must for centuries remain the chief source of heat for domestic as well as for manufacturing purposes.

LONDON: PRINTED BY EDWARD STANFORD, 55, CHARING CROSS, S.W.