COMPOSITION OF WATER, &C; 223 



The facility and promptitude with which the engineers of Facility of this 

 bridges and highways might execute this work, will be ap-**"^ * 

 parent, if it be recolleded that, at the time when the major 

 part of the great roads in France were formed, and when a 

 general fyftem of infernal communications was defired to be 

 eftablifhed, M. de Trudaine, affifted by M. Perronnet, caufed 

 plans to be taker! of all the principal roads, from their com- 

 mencement to the frontiers. There was joined to the plan 

 of the road properly fo called, that of the country bordering 

 on it, to the difiance of three or four hundred yards at each 

 fide; a work which evidently required more time than limply 

 taking the levels of a determined line, fuch as we propofe ; 

 and yet the engineers of bridges and highways, or their pu- 

 pils, employed in taking thofe itinerary plans, completed from 

 five to fix leagues of them each month. 



The general utility of the operation, of which a fketch is Geological ope- 

 here given, will fooner or later determine fome of the nations ''^'^'on^ already 



^ performed m 



of Europe to undertake it. France, on whole territory has France, urged 

 been lately executed fome of the fineft geological operations ^s a motive to 

 ... •' . , , , r r? /- /^ .• commence tlu» 



which were ever performed, and where, for the nrft time, ^wq^u.- 



^'ftem of univerfal meafure has been eftablifhed on an inva- 

 riable balis, feems to be particularly called on, to give, on 

 Ihis occafion, the firfl example of a work, which, by com- which would 

 pleting the natural geography of countries, will furnilh new tul^i* geography" 

 fa^s to geology, and to thofe different parts of natural hiftory of countries, 

 which depend on it. 



IX. 



Obfcftations and Experiments on the Compnfiiiou of Water, and 

 other Elementcuy.Doctriaes. By H. B. K. 



To Mr. NICHOLSON. 

 SIR, 



l\.S two papers have appeared in your Journal, both of 

 which militate againft the refuit of my experiment, and as Mr. 

 Accum has been concerned in one of them, I iherefore think 

 it incumbent on me Co anfwer iliem. 



K 2 I wa» 



