It is not to be supposed that so complete a system of paving existed from the beginning of the city. Some light is thrown on the period of its laying by two inscriptions,--one, EX · K · QUI, cut in the edge of the sidewalk west of Insula IX. iv.; the other, K · Q, in the pavement between the second and fourth Insulae of Region VII. Both are evidently dates, and in full would read _ex Kalendis Quinctilibus_, 'from the first day of July,' and _Kalendis Quinctilibus_, 'July 1.' Apparently they relate to the laying of the pavement; this was in place, even in the unimportant side street of Region VII, when the inscriptions were cut, and so must go back to the time before the name of the month _Quinctilis_ was changed to _Iulius_, our July. Pompeii was paved, therefore, before 44 B.C. The stepping stones were particularly useful when there was a heavy rain; for the water then flowed in torrents down the streets, as it does to-day in Catania, where the inhabitants have light bridges which they throw over the crossings after a storm. There were covered conduits to carry off the surface drainage of the Forum, one of which runs under the Strada delle Scuole to the south, the other under the Via Marina to the west. Elsewhere the water rushed down the streets till it came near the city walls, where it was collected and carried off by large storm sewers. These are still in successful operation, as are also the conduits at the Forum. One is at the west end of the Vico dei Soprastanti, another at the west end of Nola Street; and a third leads from Abbondanza Street, where it is crossed by Stabian Street, toward the south. There were other sewers in the city, but they were of small dimensions and have not been fully investigated. They seem generally to have been under sidewalks. They were not designed to receive surface water, but the drainage of houses. They cannot have served this purpose fully, however, for most of the closets were connected, not with the sewers, but with cesspools. After the lapse of more than eighteen centuries, the visitor at Pompeii will distinguish at a glance the business streets from those less frequented. The sides of the former are lined with shops; along the latter are blank walls, broken only by house doors, with now and then a small window high above the pavement. The greatest volume of business was transacted on the two main thoroughfares, Stabian and Nola streets; next in importance were Abbondanza Street, leading from the Forum toward the Sarno Gate, and the continuation of Augustales Street from the north end of the Forum toward the east. First in the list of quiet thoroughfares is the broad Mercury Street, along which were many homes of wealth; the north end of it is closed by the city wall.