problem under the coercion of the policeman’s to be enabled to bum coal without smoke, and, persecutions. They were open to observation from the bridges and the river shores, and so most of them took to using smokeless but not therefore gasless coal, and this made some difference in the more prominent parts of London; but the great mass of kitchen chimneys — the grand producers of smoke — remained and remain as before, and probably, with no other motive but coercion to restrain them, would have remained smoke-makers to the end of time, for no Government officials would have compelled them to do that in which they were not competent to instruct them.
Fortunately, self-interest in another direction has led to a simple and easy solution of the problem. The great boiler question, how to consume fuel with the minimum of waste, and also with the minimum of smoke, was long ago solved in Cornwall, where the great cost of coal, by reason of distant transit, forbade a profitable use of it — unless without waste. This was done for upwards of a score of years, and was talked of as a sort of wonder, and not believed in by those who used coal at the pit’s mouth, nor by Londoners to whom the cost was far less than in Cornwall. But one Mr. Wicksted, far and wide known as an engineer, having taken in charge the East London Water Works, where the chief business was to pump water to a great height, determined to do it at as little cost as possible for the benefit of his employers. So he visited Cornwall, satisfied himself of the facts, and erected a powerful steam engine at Old Ford, in the locality where once King Alfred changed the course of the Lea river, and set the Danish ships a-dry leaving them in terrorem like other Black Ravens.
The question of preventing smoke is simply that of mixing a sufficient (and not more than sufficient) quantity of atmospheric air with the gases which are distilled in the process of burning. If too much air be supplied, the heat will be carried off in waste, and possibly without generating smoke, just as a very small fire may be blown out and extinguished by too large a bellows. If smoke-producing coal be broken into fine dust, and gradually and thinly scattered on a hot coke fire, the gases will be rapidly distilled, and if mixed with atmospheric air in the right quantity, all the gases will be burnt, producing a bright flame, and the residue will be coke or carbon, which burns without smoke. This is merely the process adopted in Cornish boilers, mechanism being used to sift the coal-dust or small coal on to the fire.
Analyses of cost in processes of manufacture are common. Analyses of cost in the chemistry of kitchen fires is at best a rare process amongst those interested. Fortunately, a very large and influential body have become interested in smoke prevention. The legislature has forbidden the burning of coal in locomotive engines, and specified that only smokeless fuel shall be consumed. The smokeless fuels are anthracite or Welsh coal, and coke. Anthracite disintegrates and falls through the grate bars, and will not answer when violently shaken along a railroad. Coke in many cases costs double the price of coal, and as a ton of coke will not give out so much heat as a tone of bituminous coal, it becomes a very important matter consequently, without waste. Many years back this was accomplished by Mr. Dewrance on the Grand Junction Railway; but as the Grand Junction in those days paid eleven per cent., little regard was paid to savings which perhaps involved trouble and opposition. Lower dividends have now made every source of saving desirable, and scores of people have been at work to construct coal-burning locomotives, Mr. Beattie of the South-Western being the earliest in the field. Of course, if the process be complete, that which is simplest and cheapest is preferable. One by Mr. D. K. Clark fulfils these conditions. He makes, at little cost, a novel kind of bellows; an infinitesimal jet of high-pressure steam from the boiler induces a violent rush of air. As many of these bellows or openings are connected or applied above the surface of the black coal through which the gases are distilling, the jet of steam, and consequently of air, is contrived to pitch in any direction so as to mix thoroughly with the gases, in which case combustion ensues. If the mixture be not produced, the cold air may then pass through these tubes without consuming the gases, and with a diminution of steam production. But so perfect is Mr. Clark’s arrangement, that by turning off or on the steam jets, smoke maybe produced or prevented at pleasure.
What is done in locomotives may be done in house chimneys, by powerful air draughts induced by the chimney. It is no doubt possible to prevent the generation of smoke, if not in open fires, in fires partially closed in a peculiar manner. Fires are required in dwellings to be used in two ways: to produce warmed air, and to produce radiant heat. Both are required in kitchens for boiling water, heating food, baking, and roasting. The latter process cannot well be achieved without radiant heat. Again, in cold weather the general atmosphere of a house requires warming to that extent which is wholesome for breathing; but a greater amount of radiant heat is required for the feet of persons of sedentary habits, or whose circulation is slow. The heat which is pleasant to the feet, would be destructive to the lungs; and the heat which can be borne by the lungs would be almost useless to the feet.
One simple method of preventing smoke, is to feed the fuel from below, in which case the distillation carries the gases through the hot fuel; and there is no reason why this principle should not be applied to kitchen as well as to other fires. But, however, it is sufficient for our present purpose that smoke from bituminous fuel can be prevented; the details are not necessary in this present paper.
We suppose, then, a bright atmosphere — bright as that of any city where wood fuel is used, nay, brighter, for wood also produces smoke very unpleasant in a peculiar state of the atmosphere, as when a log of green elm hisses and sputters at you in Paris in winter time. And now for my gardens. But where is the space? may be asked. So may be asked, where is the space for a garden in an uncleared forest? The space for gardens in a city is equal to that of the whole of the city, less the streets and passages; in short, it is the