The other mode of avoiding the formation of mud is the substitution of wooden pavements; of the success of these I have little doubt, though for the present many failures have occurred, either from The foundation not having been truly and firmly laid, or from the blocks of wood not being massive enough. The greatest objection to wood pavements at present is the slipping of the horses, but this I believe might be obviated.
The question, however, at present is to get rid of the street dirt, such as it is; and for that purpose I apprehend it would only be necessary in wet weather during rains that the street-cleaner should sweep the dirt into the kennels, and aid the water by stirring the mud, to carry off the material in a state of diffusion; in dry weather, the opening of pipes with hose attached would serve the same purpose as the rains, and at the same time aid the sewerage at the time most required. After a short but heavy fall of rain, the cleansing effect of the water is fully perceived: and if any means could be devised of saving the rain-water that falls on the houses and in the streets, so as to apply it in considerable quantities at intervals, it is probable that the rain-water would be amply sufficient for all the purposes in question.
I have heard of the plan pursued by the West Middlesex Water Company for cleansing their reservoir at Kensington, at little expense, by diffusing the muddy deposit in water, and allowing it to run off in pipes.
In the city of Guanaxuato in Mexico, a similar mode of cleansing has been long practised; a splendid tank of ample dimensions contains the water used by the inhabitants; the tank is supplied by mountain torrents, which bring down a considerable quantity of mud or silt, and which makes a deposit in the bottom of the tank, which is formed by a fine dam of masonry crossing a narrow valley, and provided with sluices. The rainy season commences in the latter part of June, and a short time previous the ceremony of emptying and cleansing the tank is gone through; a kind of fair and holiday is held on the ground, to which most of the inhabitants resort; the sluices are opened, and as the water recedes, the watermen, boys, and all those who relish the fun, get into the tank and keep stirring up the silt with sticks and spades, &c., and in this manner the mud is annually carried off by the remaining water of the past season, a subsidiary tank serving for use until the principal one is replenished.
By some sort of a similar process it is alleged that much of the mud-banks of the Thames above the bridges have been removed, viz., by the action of the paddle-wheels of the numerous steam-boats running there. Some of the effect observed must be owing to the greater scour of the tides since the removal of Old London-bridge, though some part may also be due to the steam-boats.
For the purpose of giving more aid to the surface-water in cleansing the streets, and at the same time for keeping the footways and houses drier and more free from mud, I should propose (at least as an experiment) a different structure of the carriage-way, viz., to make it incline to a centre kennel, instead of to two side ones. At present, in many places, the centre of the carriage-way is elevated above the level of the shop doors, and at the same time we often find the footway but three inches higher than the kennel; and it is pretty obvious from this arrangement, in dry weather, the dust will blow from the more elevated carriage-way on to the footways, and into the shops and areas; and in wet weather the water and mud being chiefly accumulated in the side gutters, the carriage wheels and horses’ feet will distribute it plentifully on the footways, and not unfrequently on the passengers, and all tending to keep the houses damp and dirty, whereas it is obvious that, was the descent constant from the houses[[52]] on either side to the centre of the street, these evils would be avoided, and it will be no less evident that all the surface-water flowing to one common channel would possess more force and convenience for running the street dirt into the sewers. I am inclined to believe that the carriage-ways are getting gradually elevated above their proper level, from the contractors for paving not excavating deep enough for the foundation of the pavement.
Annexed is a sketch, showing in juxta-position the form of the street-ways as at present, and as proposed to be; the street is supposed to be a shop-street, 90 feet wide, having two areas of three feet each, two footways of 12 feet, and 60 feet of carriage-way; on the section of the proposed plan a fall of six inches, or 1 in 30, is given from the shop door to the edge of the pavement; there is then a descent by two steps of six inches each to the carriage way; and lastly, a descent of 1 in 30, or of one foot to the kennel in the centre of the carriage-way. The kennel may either be open or covered; if the latter, it must have many gratings. In the city of Mexico the kennel is chiefly in the centre of the street, and covered by large flat stones.
On the proposed plan, if we suppose a step from the foot pavement to the floor of the shop or house, the latter will be elevated about 3 feet above the gutter, whereas at present we often find it not more than six inches, and it will readily be admitted that such a difference in the disposal of the surface-water cannot but keep the houses much drier and more cleanly.
By having one gutter in the centre of the streets instead of two, (one at each side,) we remove two sluggish and inefficient kennels, which are the source of damp to the pavement and to the houses, and we create one which is at a distance and doubly effective.
The subject of street pavements having been introduced as the means of surface-drainage, it may be remarked how difficult it must ever be to keep them in good order so long as they are liable to be broken up whenever water or gas-pipes require altering or repairing, besides the extreme annoyance occasioned during that operation; and though it may not be possible to obviate the inconvenience in all cases, yet I conceive the evil may be reduced to very narrow limits by resorting to system, and I would suggest that under the foot pavements passages should be formed, lined with brick-work or masonry, as a common receptacle for all the water and gas-pipes, having the flagging over the passage so laid as to be easily lifted in case of need, and being provided at intervals with side entrances for inspection and all such repairs as could be effected without raising the flagging. The position of the gas-pipes under the foot-pavement would be convenient for the street and shop lights, and the water-pipes would be then equally so for the use of the houses. But in respect to the sewer of the street, I should propose to place it near the centre of the carriage-way, as more distant from the dwellings, but as equally convenient to both sides of the street. (See the section for new form of carriage-way.)