1 14 Mcehanic Arts, [Chap. IX. 



In the erection of Bridges modern artist* 

 have displayed unprecedent boldness and enter- 

 prise. The first biidge constructed of cast iron 

 was produced in the -eighteenth century. This- 

 was erected over the river Severn, in Shrop- 

 shire, in 177i), by Mr. A. Darky, an ingenious 

 iron-ma»ter, assisted bv the exertions of Mr. J, 

 Wilkinson, of the same profession. The second 

 iron bridge was constructed on a larger scale, over 

 the same river, in 17f)C, upon a new plan, by 

 ]\Lv Thelford* A third, on a still larger and 

 more daring scale,, was buik over the river Wear,. 

 in Durham, a short time afterwards, by Rowland 

 Burdon, et^q. To tlicse may be added the icooden 

 bridges, of several kind,-^, and on various new con- 

 structions, which have been invented in the course 

 of a ^Q\w years past, both in Europe and America, 

 and which have proved sources^ of great public 

 utility. 



In the consti'BCtion of Milh improvements no^ 

 less remarkable and impoi'tant have been made,, 

 within the period in question. Of these some 

 have arisen from the new light lately thrown upon 

 the laws of /??7^/r^z//zi'^; and others from the inge- 

 nuity and enterprise of practi-cal artists. The nu- 

 merous experiments and discoveries, and the learn- 

 ed writings which have been given to the world 

 in the course of the century, on this subject, by 

 Desaguliers, Emerson, Smeaton, Barker, and 

 Burns, of Great Britain ; by Belidor, de Parcieux, 

 and others, of France ; by Bernoulli, of Switzer- 



whidi is equal to tlie combined action of 200 good horses. Se^ 

 Botanic Garden, part i, Additional Notv xi. 



