Messrs. Lewis and Massey contemplate the use of governors in combination with various forms of their automatic gear, so as to provide for every imaginable case of winding, and also to avoid accidents when heavy loads are sent down a pit; the special feature in their mechanism being that when two or more things happen with regard to the positions of steam or reversing handles, speed or position of cages in the pit, whatever it may be necessary to do to meet the particular case shall be done automatically.

* * * * *

THE WATER SUPPLY OF ANCIENT ROMAN CITIES.

[Footnote:  An address by Prof.  W.H.  Corfield, M.D., M.A., delivered before the Sanitary Institute of Great Britain, July 9, 1885.—­Building News.]

As the supply of water to large populations is one of the most important subjects in connection with sanitary matters, and one upon which the health of the populations to a very large extent depends, I propose to give a short account of some of the more important works carried out for this purpose by the ancient Romans—­the great sanitary engineers of antiquity—­more especially as I have had exceptional opportunities of examining many of those great works in Italy, in France, and along the north coast of Africa.  Of the aqueducts constructed for the supply of Rome itself we have an excellent detailed account in the work of Frontinus, who was the controller of the aqueducts under the emperor Nerva, and who wrote his admirable work on them about A.D. 97.

It may be interesting in passing to mention that Frontinus was a patrician, who had commanded with distinction in Britain under the emperor Vespasian, before he was appointed by the emperor Nerva as controller (or, we should say, surveyor) of the aqueducts.  He was also an antiquarian, and in his work he not only describes the aqueducts as they were in this time, but also gives a very interesting history of them.  He begins by telling us that for 441 years after the building of the city—­that is to say, B.C. 312—­there was no systematic supply of water to the city; that the water was got direct from the Tiber, from shallow wells, and from natural springs; but that these sources were found no longer to be sufficient, and the construction of the first aqueduct was undertaken during the consulship of Appius Claudius Crassus, from whom it took the name of the Appian aqueduct.  This was, as may be expected from its being the first aqueduct, not a very long one; the source was about eight miles to the east of Rome, and the length of the aqueduct itself rather more than eleven miles, according to Mr. James Parker, to whose paper on the “Water Supply of Ancient Rome” I am indebted for many of the facts concerning the aqueducts of Rome itself.  This aqueduct was carried underground throughout its whole length, winding round the heads of the valleys in its course, and not crossing them, supported on arches, after the manner of more recent constructions; it was thus invisible until it got inside the city itself, a very important matter when we consider how liable Rome was, in these early times, to hostile attacks.