494 PLINTHS NATURAL HTSTOEr. [Book XXXI. 



CHAP. 31. (6.) THE METHOD OF CONVEYING WATEB. 



The most convenient method of making a watercourse from 

 the spring is by employing earthen pipes, two fingers in thick- 

 ness, inserted in one another at the points of junction — the one 

 that has the higher inclination fitting into the lower one — and 

 coated with quick-lime macerated in oil. The inclination, to 

 ensure the free flow of the water, ought to be at least one-fourth 

 of an inch to every hundred feet ; and if the water is conveyed 

 through a subterraneous passage, there should be air-holes let in 

 at intervals of every two^^ actus. Where the water is wanted 

 to ascend" aloft, it should be conveyed in pipes of lead : 

 water, it should be remembered, always rises to the level of its 

 source. If, again, it is conveyed from a considerable distance, 

 it should be made to rise and fall every now and then, so as 

 not to lose its motive power. The proper length for each 

 leaden pipe is ten feet ; and if ^^ the pipe is five fingers in cir- 

 cumference its weight should be sixty pounds ; if eight feet, 

 one hundred ; if ten, one hundred and twenty ; and so on in the 

 same proportion. 



A pipe is called "a ten-finger"^^ pipe when the sheet of 

 metal is ten fingers in breadth before it is rolled up ; a sheet 

 one half that breadth giving a pipe *' of five fingers."^' In all 

 sudden changes of inclination in elevated localities, pipes of 

 five fingers should be employed, in order to break the impetu- 

 osity of the fall : reservoirs,^^ too, for branches should be made 

 as circumstances may demand. 



CHAP. 32 — HOW MTNEKAL WATERS SHOULD BE USED. 



I am surprised that Homer has made no^^ mention of hot 

 springs, when, on the other hand, he has so frequently intro- 

 duced the mention of warm baths : a circumstance from which 

 we may safely conclude that recourse was not had in his time 

 to mineral waters for their medicinal properties, a thing so 

 universally the case at the present day. Waters impregnated 



^^ See B. xviii. c. 3, and the Introduction to Vol. Ill, 



^* In jets, he means. ^^ " Si quinariae eriint." 



56 " Denaria." 57 « Quinaria." 



=^ The name given to these reservoirs was " castelhira " or " dividicu- 

 liira :" in French the name is " regard!' Vitruvius describes them, B. vii. c. 7. 



■^ Pliny appears to have forgotten the warm springs of the Scamander, 

 mentioned by Homer in the Iliad, B. xxii. 1. 147, et^seq. 



