DRAINING OF LAKE CELANO. 417 



of soil as fertile as any in Italy.* The ground abeady dry enongli 

 for cultivation furnishes occupation and a liveHliood for a popu- 

 lation of many hundred persons, and it is thought that this num- 

 ber will be augmented to thousands when the drainage shall be 

 completely effected. 



The new tunnel follows the line of the Claudian emissary — 

 which though badly executed was admirably engineered — but its 

 axis is at a somewhat lower level than that of the old gallery, and 

 its cross-section is about two hundred and twelve square feet, 

 while that of the Roman work was only one hundred and two 

 square feet — a proportion which shows the possible dehvery of 

 water by the modern conduit to be far greater than that of its 

 predecessor. 



In consequence of the nature of the rock and of the soil, which 

 had been loosened and shattered by the falling in of much of the 

 crown and walls of the old tunnel — every stone of which it was 

 necessary to remove in the progress of the work — and the great 

 head of water in the lake from unusually wet seasons, the tech- 

 nical difficulties to be surmounted were most baffling and dis- 

 couraging in character, and of such extreme gravity that it may 

 well be doubted whether the art of engineering has anywhere 

 triumphed over more serious obstacles. 



It deserves to be mentioned, that at a most critical period in 

 the work, when the risk to the laborers was very great. Prince 

 Torlonia encouraged the men by his personal presence at the 

 most exposed points. This great "victory of peace" — probably 

 the grandest work of physical improvement ever effected by the 

 means, the energy, and the munificence of a single individual — 

 is of no small geographical and economical, as well as sanitary, 



* Springs rising in the bottom of the lake have materially impeded the pro- 

 cess of drainage, and some engineers believe that they will render the complete 

 discharge of the waters impossible. It appears that the earthy and rocky 

 strata underlying the lake are extremely porous, and that the ground already 

 laid dry on the surface absorbs an abnormally large proportion of the precipi- 

 tation upon it. These strata, therefore, constitute a reservoir which contrib- 

 utes to maintain the springs fed chiefly, no doubt, by imderground channels 

 from the neighboring mountains. But it is highly probable that, after a cer- 

 tain time, the process of natural desiccation noticed in note to p. 19, ante, will 

 drain this reservoir, and the entire removal of the surface-water will then b&- 

 come practicable. 

 18* 



