WATER SUPPLY. The improvements which have lately been effected in the practical details of civilised life, have given rise to so great a demand for a copious domestic supply of water, that the branch of hydraulic engineering connected with that portion of modern social organisation has assumed a degree of importance, in excess even of the importance attached to it by the most civilised nations of anti quity. Yet from the earliest periods in the history of man, the attention of the governors of populous cities has been always directed to providing for them copious supplies of the fluid so indispensable for comfort, cleanliness, and safety; and no surer test can be found for the character of a national organisation, so far as its influence upon the physical happiness of its subjects is concerned, than the one to be discovered in the state of the water supply of its towns. Some of the lessons to be derived from an examination of the various systems hitherto adopted will be alluded to in the course of the following review of their history.
There are few indications left of the existence of a complete system of water-works in the ruins of the Assyrian, or of the Babylonian towns, although the numerous traces of canals upon the banks of the Tigris and Euphrates show that great attention was there paid to the irrigation of the land, and to securing a copious supply of water. In Egypt, the same conditions appear to have prevailed, and numerous canals were formed for the purpose of leading the waters of the Nile to tanks, and wells, situated at distances from the shores of the stream ; but the water was not habitually raised to any height, unless in gardens, and then only in small quantities, and by very rude machi nery. It is interesting, however, to observe that the hieroglyphical paintings of the Egyptians represent the use of the shadonf, or of the balance pole and bucket, still retained in that country, and by the market gardeners of the neighbourhood of London. The noria was not known to, or used by the ancient Egyptians, although so univer sally employed in that country at the present day ; but Diodorus mentions that the machine known by the name of the Archimedean screw was invented by them. In Phcenicia, and in traces of aqueducts, of tanks, and of wells, are frequently to be met with ; and in those countries the first indications of works designed for the purpose of conducting the waters which outburst at a high level at some distance from the proposed place of consumption, may be observed. There were no pipes used in any of these waterworks, or conduits; and the first instance on record of their application is to be found in the ruins of the aqueduct of Patara, in Lycia ; upon which lino there is a singular wall, or embankment of rough stone, across a valley 250 feet deep, and 200 feet across, bearing upon its curved top a line of marble blocks cramped together and perforated, so as to form, in fact, a reversed syphon. It would seem that the defective state of the metal lurgic arts, alone retarded the application of the principles of hydro statics known to the more ancient nations of the East ; for the hiero glyphical paintings of Egypt certainly show that the syphon and the ordinary forms of pipes were occasionally employed by them ; band the aqueduct of Patara equally proves that the Greeks were aware of the Law by which water rose to equal heights in the two legs of a reversed syphon.
It was, however, under the dominion of the Romans that the ancient world undertook the most gigantic works for the supply of their towns with water ; and, fortunately, the writings of Vitruvius, Frontinus, and Palladio have transmitted to our days much curious information with respect to the detailed methods of execution adopted by the Roman engineers. According to Frontinus, the inhabitants of the Eternal City for a long time contented themselves with a supply of water obtained from the Tiber, from land-springs, and from wells ; hut about the year 312 n.e., the censor Appius Claudius completed the first aqueduct, subsequently known as the Aqua A ppia, which conducted to Rome the waters of a spring rising " in the field of Lucullus, between the 7th and Sth milliaria of the Prenestine road." Subsequently, the aqueducts of the Anio Vetus, Aqua Marcia, Aqua Tepula, Aqua Julia, Aqua Crabra, Aqua Virgo, Aqua Alsietina, Aqua Augusta, Aqua Claudia, Anio Nevus, and the A.. Alexandrina were added to the means of supply ; and in the later days of the empire the daily distribution of water amounted to the enormous quantity of 332,307,624 gallons. As the population of Rome does not appear to have attained 1,000,000 under Aurelian, according to the calculations of M. Letarouilly, the average supply must have been about 332 gallons per head per day; but as the registers of the distributions show that only one-fifth of the total quantity was taken by private consumers, it must be evident that the bulk of the water was devoted to the public fountains, baths, gardens, and amphitheatres, &c. The text of Frontinus contains many curious details with respect to the manner in which the house services were connected with the reservoirs, or distributary cisterns; the regulas tion of the plumbers' works ; and the precautions observed to insure the coolness and purity of the water ; and there are few books illus trative of the manners and customs of the Romans which give so • curious an insight into their municipal life as the • Commentaries' of this authir. It may be added that the total length of the eleven first named aqueducts was cot less Oink 456,937 yards, of which 53,421 yards were built upon arches. The point of ground in the city was the Mons Eequilinua, which was 144 feet S inches above the level of the invert of the Cloaca Maxima, but the aqueduct of the Anio Norm!' discharged its waters at the level of 155 feet 10 inches above the same datum. The flow of the waters attributed to the public service was constant, by night as well as by day ; and the private con sumer had the same p rivilege if he desired it.