Their open construction is lighter than a beam structured platform but is just as strong. The parts of a truss are the tie-beams, posts, rafters, and struts; the distance over which the truss extends is called the span. A truss is formed by connecting the ends of straight pieces of metal or wood to form a series of triangles lying in a single plane. A truss is based on the fact that a triangle is a configuration that cannot collapse or change its shape unless the length of one of the sides is changed. The two most commonly used truss designs are the Howe and Warren trusses. In 1806 the first patented bridge system, the Burr arch truss was used in the US. The Town truss was invented in 1820, in 1840 the Howe truss was invented, and in 1841 the bowstring was invented it was a breakthrough in engi

Some common words found in the essay are:
, Pratt Warren, Howe Warren, warren trusses, howe warren trusses, truss invented, howe warren, amounts weight, pratt warren, howe trusses, bridges roofs,
Approximate Word count = 537
Approximate Pages = 2 (250 words per page double spaced)