MECHANICS AND USEFUL ARTS. 29 



in was interrupted by high water for a few days in the middle of 

 February, and two piers had been lost while floating them to their 

 places,' by the breaking of guys ; but with these exceptions, 

 no mischance occurred, and notwithstanding the severity of the 

 season and the arduous nature of the work, no loss of life, 

 personal injury, or unusual sickness was suffered among the 

 70 men employed. Both the process and the result reflect 

 great credit upon the agent, Mr. Geo. W. Porter, and the 

 superintendent, Mr. A. P. Richardson, who jointly devised and 

 managed the plan. Scientific American. 



THE AMERICAN LATTICE BRIDGE. 



It may be considered as a generally received opinion among 

 engineers of the present day, that the open-web girder offers supe- 

 rior advantages, upon the whole, to the older and more solid-sided 

 form. Were any proof required of the general favor with which 

 they are now regarded by the profession, two out of three large 

 bridges erected would bear witness to the fact. When, twenty 

 years ago, a commission was appointed to inquire into the appli- 

 cation of iron to railway structures, its verdict respecting the open- 

 web form was that "lattice girders appear of doubtful merit;" 

 and Mr. Fairbairn, in one of his works, expresses a nearly similar 

 opinion. In spite, however, of all the cold water thrown upon 

 the new claimant for engineering consideration, it has continued 

 steadily to make way ; and it is interesting to contrast its present 

 position with that which was predicted for it. The disparaging 

 statements and condemnatorv arguments urged against all girders 



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of the open-sided form on their introduction, serve to forcibly 

 point out that men of scientific attainments are not exempt from 

 those foibles and prejudices which some people imagine are con- 

 fined to the less educated and instructed world at large. The 

 commission was evidently wedded to the old system, and could 

 not perceive that their favorite example embodied all the particu- 

 lar attributes and features of the ancient methods of construction. 

 Any one who glances at the two different forms, beholds in the 

 cumbersome, shapeless proportions of the solid-sided girder the 

 presence of that solidity and massiveness which formed a distin- 

 guishing characteristic of the days when science was unknown, or 

 at any rate unpractised, and when brute force was the sole power 

 employed to counteract and resist the action of external agents. 

 In the open-web beam we recognize a worthy offspring of scien- 

 tific construction. It resists the action of the strains brought upon 

 it, not en masse, as in the case of its older rival, but by that due 

 proportioning and accurate adjustment of all its various parts, 

 which can alone impart to a structure the appearance of lightness 

 and elegance ; while, at the same time, it bestows upon it all that 

 strength and rigidity inseparable from the duties it has to per- 

 form. The open-web girder, which, in its widest signification, 

 includes all those classed under the various denominations of tri- 

 angular, trellis, lattice, and truss, was borrowed by us from our in- 

 genious transatlantic brethren, who were first to erect some splen- 



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