596 PHILOSOPHICAL TRANSACTIONS. [aNNO 1779. 



all with regard to the velocity of the current there, which is often very great 

 from the compression and impulsion of the upper waters. In the 2d rate or 

 class, most artificial canals in flat countries, made for the use of navigation ; 

 especially those in the Dutch and Austrian Netherlands. The 3d rate or class, 

 the river Trent ; the Scheld and the Lys below Ghent ; the Isere and the Iprelee 

 below Fort Knock in Flanders ; many rivers in the territories of Bologna and 

 Ferrara in Italy ; the river Meander in Natolia ; and innumerable others in flat 

 countries. The 4th class, the Thames ; the Lys and the Scheld above Ghent 

 in Flanders ; the Senne, the Dyle, and the Demmer, in Brabant ; the Seine 

 and the Somme in France ; the Nile and the Niger in Africa ; the rivers of St. 

 Lawrence below Lake Ontario, the Oroonoko, the river of Amazons, and the 

 rivers of Paraguay, in America. The 5th class, the Severn and Ouse in Eng- 

 land ; the Loire and Garonne in France ; the Tagus, the Guadiana, and the 

 Guadalquivir, in Spain ; the Po and the Tiber in Italy ; the Meuse, the Rhine, 

 and the Elbe, in Germany ; the Weissel, the Neister, the Bog, and the Nieper, 

 in Poland ; the Don and the Dwina in Russia ; the Amur or Saghalien in Tar- 

 tary ; the Yellow and Blue Rivers in China ; the rivers of Cambodia, Ava, and 

 Ganges, in India ; the Euphrates ; the river Zaire in Congo ; the Mississippi. 

 The 6th class, the Rhone in France ; the Ebro and Douro in Spain ; the Da- 

 nube ; the Wolga ; the Irtisch and Oby, the Jenesca and Lena, in Siberia ; the 

 river Indus ; the Tigris; the Malmistra in Cilicia. In the /th class can only 

 be enumerated those parts of rivers where they descend from among mountains 

 into the plain country below ; as also some rivers passing through the midst of 

 mountains. To the 8th class belong all torrents among mountains ; such, for 

 example, as the Bourns in the Highlands of Scotland are described to be. 



Section 6, professes to give a general and easy method of taking levels through 

 large extents of country where rivers pass ; and also of computing the heights of 

 interior parts of continents above the surface of the sea. After which the au- 

 thor concludes with the following table, containing a summary of his researches 

 on this head. 



