The slop or surface water of the streets is conveyed to the sewer by means of smaller sewers or street-drains running from the “kennel” or channel to the larger sewers.

In the streets, at such uncertain distances as the traffic and circumstances of the locality may require, are gully-holes. These are openings into the sewer, and were formerly called, as they were, simply gratings, a sort of iron trap-doors of grated bars, clumsily made, and placed almost at random. On each side of the street was, even into the present century, a very formidable channel, or kennel, as it was formerly written, into which, in heavy rains, the badly-scavaged street dirt was swept, often demanding a good leap from one who wished to cross in a hurry. These “kennels” emptied themselves into the gratings, which were not unfrequently choked up, and the kennel was then an utter nuisance. At the present time the channel is simply a series of stone work at the edge of the footpaths, blocks of granite being sloped to meet more or less at right angles, and the flow from the inclination from the centre of the street to the channel is carried along without impedimen or nuisance into the gully-hole.

The gully-hole opens into a drain, running, with a rapid slope, into the sewer, and so the wet refuse of the streets find its vent.

In many courts, alleys, lanes, &c., inhabited by the poor, where there is imperfect or no drainage to the houses, all the slops from the houses are thrown down the gully-holes, and frequently enough blood and offal are poured from butchers’ premises, which might choke the house drain. There have, indeed, been instances of worthless street dirt (slop) collected into a scavager’s vehicle being shot down a gully-hole.

The sewers, as distinct from the drains, are to be divided principally into three classes, all devoted to the same purpose—the conveyance of the underground filth of the capital to the Thames—and all connected by a series of drains, afterwards to be described, with the dwelling-houses.

The first-class sewers are found in the main streets, and flow at their outlets into the river.

The second-class sewers run along the second-class streets, discharging their contents into a first-class sewer; and

The third-class sewers are for the reception of the sewage from the smaller streets, and always communicate, for the voidance of their contents, with a sewer of the second or first description.

As regards the destination of the sewers, there is no difference between the Middlesex and Surrey portions of the metropolis. The sewage is all floated into the river.