Irn^provement in the Constmction of Bridges, S^c. 279 



twenty years' experience in bridges, the patentee feels confident 

 of no one fact, in science and practical mechanics, more than 

 this, that the wider the spans are adopted, the greater, by far, is 

 the strength and darabiUty of this last improvement, when suita- 

 bly executed to such width of span, compared with any other 

 mode of construction now in use. If, indeed, this were not the 

 fact, beyond a doubt, in the mind of the patentee, he certainly 

 not only would not trouble himself with its introduction into 

 public use, but would promptly admit that this, or any other mode 

 not possessed of such- principles, would neither be entitled to the 

 credit of a " general system," or be possessed of any other ad- 

 vantages worthy of public confidence or patronage. 



It has ever been his opinion, even from the^rs^, that this mode 

 of combining materials, when properly perfected by practical ex- 

 perience, was such as not only to possess all the advantages that 

 science could render in its mathematical principles, but also to 

 have the immense ad vantages. of the application, in its mechani- 

 cal execution, of materials, which may be procured in any 

 part of the country, with the greatest ease, dispatch, and econ- 

 omy. 



It is also found, in a long practice of this particular principle, 

 that the advantages in the mechanical execution, by using light 

 timber, combined of sawed planks, and by a distribution, there- 

 fore, of the strain or weight to be overcome, into such an almost 

 innumerable number of nearly equal parts, that the strength of 

 any material, even the softest pine, becomes abundantly sufficient 

 to sustain its portion of such strain ; and the mode, also, of se- 

 curing each and every part of the construction, without the aid 

 of iron, becomes practicable — so amply sufficient as to ensure 

 strength, rigidity, and durability, to a degree, most certainly not 

 to be even very nearly approached by any other system of com- 

 bination and mechanical execution in practice. The great and 

 equal distribution of the material, in the sides or trusses of the 

 bridge ; the immense number of intersections or crossings of the 

 timber, in each truss, which are, each and all of them, thoroughly 

 secured by four, three, or two haj-d ivood tree-nails, of two inches 

 in diameter, according as each particular intersection may require, 

 in the importance of its situation for the purpose of bearing its 

 part of the strain ; and, lastly, and by no means the least impor- 

 tant, the advantage gained in this mode, which has never been 



