Improvement in the Construction of Bridges, §c. 277 
smaller openings ; whether the piers and abutments are of stone, 
framed timber upon mud-sills, or piles driven into the bed of the 
river. 
Economy of expense, great strength, durability, and a level 
toad-way, united in a general system of building bridges, &c., 
Suited to any part of the United States, which may be con- 
structed of such materials as can be obtained in any part of the 
country, are what is attempted, and it is confidently hoped have 
been accomplished. 
‘The subject is here explained in a general manner, with re- 
marks, also, on some of the disadvantages which have heretofore 
attended the other modes of construction, which, by this i improve- 
ment, have been guarded against or obviated. 
A quarto pamphlet has just been published, and may be had at 
the principal bookstores in New York, giving a very minute de- 
Scription and explanation, by engravings and otherwise, of the 
principles, as well as the practical and mechanical execution, in 
detail, of all that appertains to the construction of the esegeaps s 
latest improvements. 
A model may be seen at the Patent Office, Washington City, 
and at the American Institute, back of the City Hall, City of 
New York, at which latter place the patentee. may be found, or 
letters post-paid, directed to him there, will be 'prociiptly at- 
tended to. 
The great and increasing use of wooden bridges, and the fre- 
quent obstruction by freshets and other accidents, in this exten- 
Sive country, intersected with its rivers, immense both in num- 
ber and magnitude, render unnecessary any a improve- 
ments introduced ; especially if either the oui annual amount 
of capital expend. or the important daily use of bridges for 
roads, railroads, é&c., be considered. 
The patentee’s former improvement in bridges, in 1821, was 
published jn the American Journal of Science of that year, and 
subsequently i ina pamphlet, but too brief for that correct illustra- 
tion of the subject which is to be found in the pamphlet now re- 
ferred to, for this last improvement, or in the general manner 
which here follows in describing it. It consists principally in 
the introduction of two, or in some cases more, series of truss- 
braces, diamonds or lattices, by which two very important advan- 
tages have been realized, neither of which, it is believed, could 
be realized to an equal extent in any other manner, viz. 
