On examination of the stream that issues from the hole, it will be found to taper off considerably at half an inch from the distance of half the diameter of the hole. If a short tube of the same diameter be inserted in the hole, the discharge of water will be greatly increased, and if at the distance of not more than two or three diameters, this tube should be made to flare gradually, or assume a conical shape, the volume of water passing would be more than doubled, as compared with the discharge throvigh the hole, without any tube. The principle upon which this is accounted for is that of capillary attraction, for if the interior of the conical tube be smeared with tallow, or any other substance which does not readily coalesce with water, the effect ceases.t This increased discharge is not confined to circular or conical tubes ; the sides of a channel may be straight and its section a triangle or square, as well as a circle. It was to guard against frauds of this nature, that the Roman Calix was adopted a ;

short bent tube of brass or bronze, that formed the communication between the castellum and the leaden pipe for the supply of private houses, which pipe, by a Senate decree, was required to be of the same diameter as the calix, for the distance of fifty feet from the castellum.J The proportion in which the prodigal water of the Roman aqueducts was distributed, is given with great minuteness by Frontinus. The general result is, that of the aggregate supply of 14,068 quinariae, 4063 quinariee, were distributed without the city, (extra urbem^) of which 1718 were in the name of Caesar, and the residue to private use. The remaining 9955 quinariae were conveyed into the city, and received into 247 castella as well public, as private ; 3847 quinariae were appropriated to private use ;