1887.] NEW YORK ACADEMY OF SCIEN(;ES. 155 



have diverted, for a time, public interest from the highway ; 

 formerly, in the time of the old stage-coach, the source of many 

 peculiar delights to the traveller. 



We are now rattled over bridges and whirled through tunnels 

 at a speed which precludes more than an unsatisfactory glimpse 

 of the scenery which seems to flit by us ; comfort, safety, and. 

 speed fill the measure of our expectations. But the change has 

 caused our highways to be neglected, and even in the great 

 thoroughfares which lead out from our cities and towns the 

 iron bridge seems to have driven out the more beautiful and 

 durable structures in stone, which ought here, at least, to oc- 

 cupy their proper places. There is no internal improvement 

 more imperatively demanded in this country at the present 

 time than systematic reconstruction and maintenance of our 

 highways. 



Viewed as intellectual and mechanical achievements, however, 

 the great bridges of modern times are to be classed with steam- 

 ships, locomotives, and pumping-engines, which could not have 

 been suggested a hundred years ago by the most vivid imagination. 

 They are triumphs of science rather than of art, and as such we 

 should, perhaps, be content to look at them ; deriving our in- 

 terest from cold, unimpassioned reflections upon the thought, 

 the genius, and the skill which have produced them, rather than 

 from any such pleasing emotions as arise when we look upon 

 some of the works of the same kind of the older bridge archi- 

 tects. 



Famous Bridges. 



The most ancient bridges of which we have any precise knowl- 

 edge were built by the Romans, all those of a permanent char- 

 acter having been arched masonry bridges. It is certain, how- 

 ever, that such bridges were built in China many centuries ago, 

 but of their history little is definitely known. 



Of the Eoman bridges, that erected by Trajan across the Dan- 

 ube is said to have been the most magnificent. It consisted of 

 nineteen arches, each 170 feet span, the piers rising 120 feet 

 above the foundations. The width of the bridge was 60 feet, 

 and its total length 1,500 feet. This bridge was destroyed by the 

 immediate successor of Trajan, Hadrian, for fear that it might 



