470 



FOURTH REPORT — 1834. 



Although the lock had been long known in Italy, its introduc- 

 tion into France did not take place until the reign of Francis the 

 First, when a lock was erected on the river Ourcq, by Leonardo 

 da Vinci. The improvement of the na\'igation of tlie Seine, and 

 the junction of the Seine and Loire, were preludes to the execu- 

 tion of the canal of Briare under Henry the Fourth, in the year 

 1605, terminated in the year 1642 under Louis the Thirteenth, 

 and which was followed by the canals of Orleans, of Lourg, of 

 Beaucaire, and the junction of the Mediterranean and the Atlan- 

 tic seas bj'^ the celebrated canal of Languedoc, executed by Riquet 

 in the reign of Louis the Fourteenth, so well described by La- 

 lande, Andr^ossi, Gauthey, &c., and since made the subject of 

 the scientific researches of Navier, Prony, and Girard. The 

 works of Huerne de Pommeuse, of Becquey, of Brisson, and 

 Dutens show the advanced state of the canals of that country. 



The following is a general statement of the canals of France, 

 according to M. Dutens. 



On the subject of regurgitations, or the swelling of rivers, by 

 obstacles placed in them, such as dams, weirs, jetties, bridges, 

 or contractions of their channels, it only remains to notice the 

 experiments of Eytelwein, Bidone and Funk. 



An abstract of E}i;elwein's experiments, by the late Dr. Young, 

 has already been given in the former part of my Report. When 

 the motion of a river is obstructed by a dam placed directly 

 across it, the surface of the river rises, and the water passes over 



• The author of this paper is indebted to M. Le Grand, Directeur General 

 des Ponts et Chaussees, &c., Conseiller d'Etat, for a detailed statement of the 

 canals of France, from which the total length of the seven great lines of junction 

 is 3,679,033 metres. 



■f Rapport ati Rot Louis XVI 1 1, pour Van 1820, sur la Navigafioti Interieure 

 de la France : par M. Beequery, Conaeiller d'Etat, Directeur G6ncral des Ponts 

 et Chausses. 



