Aqueducts of tubes have this advantage if any damage happen, any person may rectify it, and water from earthen tubes is far more wholesome than that from pipes, as the use of lead is found to be pernicious. We should not, therefore, conduct water in pipes of lead, if we would have it wholesome. The taste also of that from the tubes is better, as is proved by our daily meals ; for all persons, although they have tables furnished with silver vases, use fictile ware on account of the purity of the water.

We add to this detailed extract from Vitruvius, the directions of Pliny for water conduits, chiefly because of the explicit assertion it contains of the law, that fluids will

always rise to the level of their head. " " a man would says this author, If," convey water from any head or spring, the best way is to use pipes of earth made by the art of the potter, they ought to be two finger's thick, and one jointed within another, so that the end of the upper pipe enters into the end

of the under one, as a tenon into a mortice, or a box into the lid ; these pipes ought to be

laid even with quick lime, quenched and dissolved in oil. The least level to carry and command water up hill from the descent is 100 feet, but if it be conveyed by one canal only, it may be forced to mount 240 feet. As touching the pipes by means whereof the water is to rise aloft, they ought to be of lead this is also to be observed, that the water ;