Excerpt:
Addressing the shortcomings of the Burr truss, namely its expense and specialized labor, Ithiel Town patented his lattice truss design in 1820. The lattice design fastened simple, diagonally set planks with treenails, or wooden pins, into crisscrossing truss system secured by top and bottom chords. Thus, Town's truss eliminated the need for large and expensive timbers, used in the Burr truss' series of arches, and streamlined the intricate, time-intensive labor of fastenig mortice-and-tenon joints into the simple slotting and wedging of treenails. Town's innovative truss design is visible today in two of Connecticut's three remaining covered bridges, Bull's Bridge in Kent and West Cornwall Bridge in Cornwall and Sharon.
Annotation:
Diagram of the patented lattice truss and detail photograph of Town's treenail joints.