“To sweep snow from the footwalks whilst the fall of snow continues, and especially during business hours, appears to be wasteful and futile, and to apply salt during the same periods may be held to be injurious to health. “That the snow of an ordinary fall can be removed from the footwalks by an application of salt an hour or so before they are scraped is an ascertained fact, except at least when a moderately severe frost has preceded, accompanied, or followed the snow-fall, or when the snow has drifted into extensive accumulations. Were it not for the danger to health by excessive cooling of the air, and for the expense attending the operation, all the impervious pavements could be cleared of snow (unless the fall was a heavy one) in a comparatively short time by a liberal application of salt and the employment of the horse sweeping machines as soon as the snow had become sufficiently softened to admit of their use.” [171] In the metropolis of London alone, the watering of the streets and roads employs, in addition to a staff of inspectors and foremen, about 1500 men, and an equal number of horses and carts; and in order to lay the dust effectually, about 30,000 tons of water must be spread upon the streets every dry day, the cost of this gigantic work being nearly 200,000_l._ per annum upon an average of 120 days when watering becomes necessary. [172] In Rouen, where chloride of calcium is obtained from the manufactories of pyroligneous acid in the neighbourhood, it is mixed with the water for use on the roads, and it is stated that on a mile of road, 16 feet in width, 5630 gallons of water were necessary daily, but that the same result was attained with 1480 gallons of chloride solution, marking 30° Baumé, and costing about ¹⁄₂_d._ per gallon, the humectation remaining good for five or six days with the solution of chloride. With water only in 1093 yards, in four rounds daily, 3520 gallons were used, the cost being 48_s._; with chloride of calcium the cost was 32_s._ per day. [173] Amongst the questions which I addressed to the surveyors of the principal towns of England in 1879 was the following:--“Is the house refuse collected by the sanitary authority or by a contractor?” and out of the ninety towns from which I received replies, only thirty were found to employ contractors for this purpose, and of these the authorities of two of them proposed to dispense with the services of the contractor, and to administrate the work with their own staff, as they found the existing state of things was thoroughly unsatisfactory. CHAPTER XX. SEWERAGE. The Public Health Act 1875 contains a considerable number of clauses dealing with the subject of the sewers of a town, but two of the shortest sections in the whole Act, and yet those that involve a considerable amount of work in the town surveyor’s department, are the following: