'320 t^YELS- OF fsa:^ce.' 



tt Is evident, that thefe lines would reprefent the borders 



of the coafls of the Tea, if it was fuppofed that its mean level 



fliould be elevated fuccefliv^ely to the fame heightbs wjiicli 



they reprefented. 



M. Trie! pre- jt vvas according to this idea that M. Diipain Triel pre- 



of a map on this P^""^^ ^ ph)fical chart, mentioned by M. Lacroix, member 



pl2"« of Liie National Inftitute, in his introdudion to Pinkerton's 



Geography ; a chart which, from the defe(5t of materials ne- 



cefTary for its conftruclion, prefented only the (ketch of a 



work, the extent of which would require for its perfedion an 



union of means, which could not be at the difpofal of any 



particular individual.* 



The order has been pointed out in which this work oii£:ht to 



be executed, and we fliall now examine how it thould be 



performed. 



The couifes of The bed of each of the great rivers mud be divided into a 



the great rivers certain number of portions, and each portion Qiould be le- 



ftnuld be di- f > * . 



■vided into por- veiled by obfervers, who (liould operate at the fame time. 

 tions, and the Thefe obfervers fliould place accounts of their operations 

 kvels of each . ' . r i i r • i i ■ i i 



tal<en byobfer- at each extremity or the portions oi the batons with which they 



yers at the fame yvere charged ; and as the levels of the fecondary rivers (hould 

 ^^' be conneded with thofe of the principal rivers, it would be 



neceflary alfo to place accounts of the operations at the mouth 

 of each of the influent ftreams. 



The levels fliould be taken on the bankj of the rivers, with- 

 out any regard to the furface of the water. U it were thought 

 ufeful to determine the declivity ot this furface, it would be 

 eafy to afcertain it, by levels taken at the fame lime with the 

 others, at certain diftances from each other. 

 The refults to When the different obfervers have completed their refpec- 

 ^« '^o'"^^^/;"^" live obfervations, the refults muft be coUeded, to form the 

 tem. feries of levels of one of the beds. And in the fame manner 



the levels of all the reft (hould be obtained. 



After this, a general fyftem fliould be formed from thofe 

 particular levels, by conneding together the different beds, 

 by operations direded from one to the other, according to 

 thofe lines which would afford the greatefl facility. 



* Compare this with Mr, Churchill's plan, at p. 224 of our 

 Xlth. Vol.—T. 



There 



