The retention of this Bye-law will, of course, prevent the replacement of the old flag-stones upon the reconstruction of the Slaughter-houses, and involve the owners in some expense. A smooth jointless pavement for Slaughter-houses was unanimously considered the best at a meeting of the Royal Institute of British Architects, in a discussion which followed the reading of a paper by Mr. Darbyshire, on Public Abattoirs, 1st February, 1875. The Metropolitan Board of Works is quoted by the “Butchers’ Trade Society” as sanctioning the use of flag-stones, but this is scarcely ingenuous, the truth being that the Board recommend _asphalte_ in the _first instance_, but allow flag-stones set in cement as an _alternative_. The advantage of placing the gully _outside_ the Slaughter-houses, is that it prevents the admission of solid matters into the drains, and provided the floor be laid at a proper inclination towards the door, all fluid materials can be readily conducted thence by gravitation into the drain beyond, by means of sunken stone channels, or cast-iron boxes having hinges, without the creation of unavoidable nuisance. These channels should be provided at certain intervals with what are termed “grids,” which prevent anything but liquids passing into the drain or sewer. “The _grids_ are hinged to fall back against the walls, and, on being opened, reveal a cast-iron box or chamber, with a flange all round the top edge, which rests on a rebate cast on the outer shell; this box is movable, and is perforated through the bottom and sides; under the movable box is another chamber opening direct into the trap, which is cast to the outer shell of the frame work.”--(Darbyshire on Abattoirs.)--These grids are in daily use at Manchester and elsewhere, and are made by Bunnett and Co. The scavengers should attend to the movable boxes at regular intervals, and cart away all solid matter. In the Edinburgh Abattoirs there are “two distinct sets of drains, one for the surface water, which is conveyed directly into Lochrin burn, the other for the soil, which is conveyed into large tanks, prepared for its reception, and sold for agricultural purposes.” (_Encyclopædia Britannica._) It is impossible to over-estimate the importance of excluding blood, offal or dung, &c., from the sewers at all times, but especially in seasons of epidemic zymotic diseases, and it would be an inestimable boon, and one by no means difficult of accomplishment, if the Scotch system could be imitated at Aldgate. BYE-LAW II.