194 PraBice Part 11. 



The Ancients had three Ways of carrying Water, by 

 Aqueduds under Ground, by Pipes of Lead, and by Pipes 

 of Earth or Potter's-Ware, which are ftill very much inUfe, 

 vicruvius, and to thefe we have added but two, which are Wooden* 

 i.vm.c.7. pipes^ and thofe of Iron. 



SuBiERKANEous Aqueduds ought to be well buik 

 with Free-ftone, and cover'd over with arched Vaulting, or 

 * Dalles ars iiat Stones, which the French call Dalles^ that the Sun.; 

 TlneTj^hii "^^y affed the Water : If you meet with a Rock, the 

 areufedin Vault may be cut out of it 5 and if fome Hill prevent the- 

 Prance tore- Paffage, you muft pierce through it, or carry the Aquedu6t 

 McQn7es]^^^^ roundabout, making Vent-Holes at every 50 Fathom, to 

 give the Water a little Air. The Bottoms and Valleys, cal- 

 led Ventres by the French^ which interrupt the Level of the 

 Conduit, fliould be filled up with Rubble-Work, and folid^_ 

 Walls of Mafonry, or with Arches and Peers, as is done in 

 the Aqueduct of ArcueiL 



The Water is conveyed through thefe AquedutJts feveral 

 ways ; ia Pipes of Earth or Lead ^ in Channel-Stones of 

 Mafonry, which' is the moft ordinary ^ or in Gutters made 

 of Lime and Mortar ; or of Clay, in Countries where it is 

 |)lenty. Sometimes you meet with natural Veins of Gravel, 

 Sand-Stone, upon which the Water will run without 

 lofing itfelf. Two fmall Paths fliould always be made up- 

 on the Sides of thefe Troughs or Channels, that you may 

 go in, and walk along them when it is neceffary ^ and be- 

 lidesthis, a fmall infenfible Fall fliould be given thefe Chan- 

 nels, to add a quicker Current to the Water. 



These Sorts of Aqueducts are proper only for colledling, 

 (of Springs, and carrying them into a Referver; for the 

 Water not being confined, as it is in Pipes, lofes jts Fall, 

 and the Force it fliould have to throw it up into the Air. 



Pipes of Lead are the moft convenient for conveying of 

 Water. You may fink them down, raife them up, or turnr 

 them afide, without any Prejudice to the Water that runs in 

 •them. Of thefe there are two Sorts, the Mould-Pipes, and 

 the Solder'd. The firft are caft in a Mould, of what Length, 

 you pleafe, ufually about twelve Foot long ^ they are made 

 iiicker than the Solder'd-Pipes^ for.fcar of blowing^ fo that 



they; 



