469 



lake of Thrasimene. The Arno, in the cele- 

 brated voltata which it makes toward the south, 

 the west, and the norths between Ribiero and 

 Ponta Sieve, divided itself near the Arazzo into 

 two branches, one of which went to the sea by 

 Florence and Pisa, as at present ; and the other, 

 after having followed the Val de Chiana, mingled 

 it's waters with the Tiber, either immediately, 

 or after having confounded them with those of 

 the Paglia. Mr. Fossombroni has shown how 

 in the middle ages, from the effect of deposits 

 of earth from the river, a point of partition was 

 formed in the Val de Chiana; and how the 

 northern part of the Arno T ever in now flows 

 {on a eounterslope) from south to north, from 

 the little lakes of Montepulciano into the Arno # . 

 The classical soil of Italy contains then, among 

 so many prodigies of nature and of art, one of 

 those bifurcations, of which the forests of the 

 New World display another example on a much 

 larger scale. 



I have been often asked since my return from 

 the Oroonoko, whether I were inclined to be- 

 lieve, that the channel of the Cassiquiare would 

 be choked up by successive accumulations of 

 earth; and whether I did not think, that the two 



* Carte d'llalie de Bacler Dalbe, No. 18, 23, 24. Fossom- 

 broni, Memoria idraulica sopra la Valde CHana, 1789, p. 17. 

 Prony, on the hydraulic system of Italy, in the Journal de 

 i'Ecole Poly technique, vol. 4, p. 02. 



