care is taken in disposing of waste matter that may find its way into the air. No doubt more is being done in this direction than in former days, but the rapid concentration of living quarters and industrial shops brings with it new conditions. It should be remembered that it is our pressing duty, and part of that civilization which has built cities for millions, to keep them not only inhabitable, but healthful, wholesome and pure. Elbert Hubbard in the course of his travels once observed that 'The path of civilization is strewed with tin cans' This certainly insinuates that we have not yet arrived, while tin cans and a multitude of other witnesses of neglect in civic duty are seen along the path.
The Smoke Nuisance.—Smokeless combustion is not only feasible for almost any kind of coal, but more economical if properly attended. The principal difficulty exists in the design of the proper furnace to suit the fuel and to meet the conditions under which it is burned. There ought to be no restriction on the use of bituminous or any other coal. On the other hand, no excuse should be accepted for black smoke from any source within city limits. If not willing or able to suppress it, the offensive industry must be made to move. But all the smaller and innumerable sources of medium, light and invisible smoke should also receive attention. They emit, in reality, by far the largest share of it in the average commercial and residential community, less noticeable because more diluted, but none the less objectionable. The reduction of this smoke is, for practical reasons, beyond control of local health authorities, but it can gradually be eliminated through individual action; that is, by the general concentration of light, heat and power service. The movement in this direction was started long ago with the introduction of central stations for light and power, but it is capable of much greater extension, particularly for heating and power. The bulk of the fuel should be burned at the mine, or at tide-water outside of city limits. Such concentration of combustion for various needs represents a material saving in the total amount of fuel consumed, and, therefore, of the smoke produced. It would incidentally avoid the handling of much coal and ashes and reduce the large amount of exhaust steam now seen pouring away from the numerous individual plants in certain neighborhoods. On still days, these vapors contribute perceptibly to the murkiness of the atmosphere. The use of steam power for transportation in urban and densely populated suburban districts has long since ceased to be a necessary evil and should have been prohibited years ago. It is gratifying to state that at last this much-needed economic and sanitary reform seems about to be realized.
Street Dust.—Dust of the streets is one of the principal elements in polluting the atmosphere. It is made up of innumerable substances utterly defying description. To what extent it permeates the air, even
