reaches in some localities 20 in 10,000, smoke-particles are thick together and oppressive, so as to interfere with breathing, and organic impurities proportionately high. Would not a large percentage of persons, either with or without the presence of an epidemic malady, succumb to the prolonged supply of a respiratory diet so poisoned?

Experience concerning the cattle at Islington in 1873 and concerning the people of London in 1880 indicates that at any rate the killed might be many thousands, and the injured hundreds of thousands.

London has very greatly extended the area of population and contamination since 1880. Apart, then, from the saving of 3,000,000l. to 5,000,000l. a year by better arrangements for the combustion of fuel, there is the question of deliverance from a possible calamity.

Immunity from dark fogs, from specially obstinate fogs, and from the dark and sunless obfuscation familiar to dwellers in our large towns, may be obtained by several distinct means, or by all of them together, applied respectively when and where convenient.

Factories are enabled to consume their smoke, or, rather, to avoid producing appreciable smoke, by various ingenious appliances which need not be mentioned. Some factories have already saved by their use in a few years several thousand pounds. The continued emission of black smoke from any chimney except of a private house is now illegal in London.

Smoke from kitchen-fires may be much diminished by the use of economical and properly constructed kitcheners or ranges, by careful stoking, and by the use of the least smoky coal broken to a convenient size. Gas-ranges and ring-burners are also very convenient, and may even in some cases save expense where carefully attended. If the price of gas were largely reduced they would be very generally used, and would save much expense in servants' time, cellar-room, cleanliness, chimney-sweeping, and the various effects of a dirty atmosphere.

Public kitchens and restaurants, with arrangements for the supply of meals at private houses, will no doubt gradually increase in number and will economise coal and diminish the pollution of the air by many carelessly tended private ranges.

Ordinary domestic fires admit of great improvement by the adoption of the proper economical principles for slow-burning, adequate but not excessive supply of air, forward sloping fire-backs, and reduced size of chimney. Anthracite coal, gas, wood, and oil are practically smokeless, but all are too expensive to be commonly used. Gas-fires answer very well for sick-rooms and for small rooms only used for a short time, or where the sparing of service is important. Screens of thin glass fitted close to the frame of the fireplace, may be used in some cases with advantage, for though they arrest

and reflect some of the heat, they may be made to diminish greatly the current of air through the room and up the chimney. Coke may often be economically substituted for coal, and except on first lighting gives little smoke. For moderate-sized houses, where much coal is burnt, hot-water pipes to landings and to two or three rooms from the kitchen boiler may be economical as regards fuel and service; but in small houses, which are the majority, the saving of extra expense would depend on the number of fires previously kept going, and on the temperature required. Where only one fire is commonly kept alight, any extra heating appliance would clearly be used at an extra cost, but might be valuable for keeping rooms dry and healthy.

In large houses and in new hotels an excellent system of heating by hot water is now much used, by which every room is maintained permanently at a comfortable temperature in the coldest weather. This has the great advantage of keeping the rooms in good condition and of allowing windows to be often open without too much chilling. The saving of expense in coal room, wear and tear, coal-scuttles, fire-irons, &c., sweeping, dusting, and service generally, and in the increased amenity which favours health and workingpower must be very large.

Systems of heating whole blocks of houses by steam are said to be much in use in the United States and Canada. Such a system, with three miles of pipes, has long been used for 200 houses in the town of Lockport. The steam is available for cooking-purposes. Probably steam-heating might well be used for rows of houses in London, and might be obtained at moderate rates in districts which desired large installations. But the mild spells which occupy so large a part of most of our winters make expensive common supplies generally superfluous for small houses, and we must continue to rely much on the separate coal or gas fire in each detached dwelling, with such improvements as may be effected for the sake of private and public economy. Flats and blocks ought certainly to be warmed by hot air, steam, or hot water, instead of the miserable ugly fireplaces still in vogue.

The very large employment of electricity for lighting-purposes ought to have led before now to an important reduction in the price of gas, for, having cheap oil and electric light, we could do very well without it. In the future coal-gas will be supplied rather for heating than for lighting. The advantages of heating and cooking by gas in small houses are so agreeable to the consumer, and the purification of air is so vital an object for Londoners, that every possible facility should be given for a cheap domestic supply and for fixing the necessary appliances at a very low rental. If the gas-works were the property of the public, as in some of our great provincial towns, there would be no difficulty in supplying gas for heating cheaply and

with great economy to the community. The indirect gain by the reduction of smoke, soot, darkness, and persistent fogs would be enormous. Public buildings and works of art would be saved from rapid decay. The municipal ownership of gas-works is really more important in some respects to a large town in this country than the ownership of the water-supply. The common use of gas for heating and for power would clear the streets of much heavy traffic which, in the conveyance of coal for long distances, now wears down the pavement and hinders circulation. It would diminish the blackening of all light-coloured internal and external objects; it would improve the climate, and reduce housework. Each of these items represents a saving of hundreds of thousands of pounds..

Parliament has given the gas companies a monopoly of supply; it would certainly seem to have the right to abolish the monopoly on very moderate terms of purchase, or to insist on a large reduction in the price of gas for heating-purposes. Municipal ownership in other matters has been proved to be far more beneficial to the public than company ownership, however supervised and regulated.

Meanwhile, improvements in the domestic modes of burning raw fuel might be enforced by some system of fines, and the law regulating the emission of black smoke might be extended to private houses.

There would be some advantage in the preparation of forecasts of heavy fogs as of gales and storms. From a long series of investigations on the formation of thick haze and fog, I have come to the conclusion that in many cases it will be possible, from certain local as well as general symptoms, to predict, at least a few hours beforehand, the occurrence of dangerous fogs. To state the governing conditions broadly: we may expect to be free from fog so long as (1) the lower and upper currents of the atmosphere move from the same or nearly the same direction, and (2) the wind moves uniformly from about the same direction within a radius of about 100 miles horizontally. On the other hand, we may expect dense fog in winter, or haze in summer, when, with copious radiation, clear or nearly clear sky, increasing cold and calm or a slight wind, the lower and upper currents or two lower currents, within a moderate distance of each other, move from opposite or greatly differing directions. The amount of haze or fog in these conditions, however, depends very largely on the difference of temperature of the two currents, and if they do not much differ there may be no fog. The worst fogs take place with the largest terrestrial radiation, the intimate mixture of two currents much differing in temperature, and prevailing calm or light airs.

Observation of the movements of high clouds, and especially of cirrus and cirro-stratus, is thus of much use for the prediction of fogs, but in the London air during calm conditions these clouds can seldom be seen. Therefore some high ground in the neighbourhood should be chosen for the purposes of forecasting; and if a small

balloon were to be sent up daily about 20,000 feet with a recording thermometer and hygrometer, valuable data would be obtained. At a height of 900 feet in Surrey there is often a slight breeze, with sunshine, while the low ground remains becalmed and foggy for a whole day. During the recent frosts in November, with heavy black fogs in London, the temperature at an altitude of 900 feet was eight or ten degrees higher than on the low ground-not only during the brilliant sunshine of the daytime, but an hour before sunrise. Perfect calm is rare at this altitude.

In some cases fog depends on merely local currents, and can hardly be foretold, but the conditions in which it is likely to occur are easily understood.

So long as a broad and deep uniform current, either dry or moist, blows over these islands, fog will not easily form; when breezes are slight, irregular, differing in temperature, and shallow, with excessive radiation from the surface of the earth, haze or fog will be found over the whole area to which they extend.

Excessive moisture is not at all necessary, and is compatible with visibility; on the contrary, the densest fogs take place when the whole upper and middle air is unusually dry and pervious to radiation.

Sea-fogs, which invade our coasts chiefly in summer, depend on large differences of temperature between land and sea. Hill fogs are, of course, clouds, and are commonly formed in quite different conditions from those which give rise to stratus, the basis of London fogs. They are refreshing to the benighted citizen, if he has not lost the capacity of breathing.

There are, after all, compensations for removal from the brick wilderness by a centrifugal impulse depending upon causes which are mainly physical. For the future of the British race confinement to a vast town is as fatal as settlement in the tropics.

ROLLO RUSSELL.

THE KITCHEN WAGGON

IT

It may be remembered that at an early period in the South African War it was commonly stated that if the troops would only take ordinary precautions and boil their drinking-water-an operation that seems so simple to the householder-much of the suffering and loss caused by the prevalence of enteric fever would be avoided. It is hardly an exaggeration to say that at one time no regiment left England for Africa whose officers had not a fixed resolve to drink nothing unboiled, and that it was only after some experience of campaigning that the practice was discontinued.

It

The theory has lately been more forcibly revived, and a meeting, attended by several prominent medical men, has been held to discuss a proposition put forward by one of their number who, taking his stand upon these grounds, has suggested that if the proper precautions were taken by the authorities, enteric fever would not only be greatly reduced, but would be rendered so uncommon that anyone found to have contracted it would stand convicted of having broken regulations and acted in an unsoldierly and disgraceful manner. is proposed that the reduction in the number of patients should be effected by compelling all ranks to drink boiled water, and in order that a sufficient supply may be available it is suggested that an organisation to be called the Royal Water Corps be formed and provided with vessels capable of dealing with all the water that may be required for drinking-purposes, and fitted with special appliances not only for boiling, but for cooling the water within a short space of time. Under these conditions it is argued that those who drink only the water supplied by the Corps will escape the disease, whilst those who contract it will in nearly every case be found upon examination to have brought it upon themselves by drinking unauthorised water. It is, of course, for the doctors to decide what benefits might be expected from this experiment; to what extent enteric fever is spread by water alone; and what degree of immunity an army might obtain by resorting to this somewhat drastic measure. The military authorities have then to be consulted as to the possibility of its introduction, and it is only natural to believe that the increase in transport and addition to the non-combatant strength will always weigh heavily against