The covered bridge also afforded an opportunity for robbers to ply their trade. It was easy to hide in the deep shadows, pounce upon the unsuspecting wayfarer, and despoil him of his possessions. Murderers also lurked in those dark confines. Crimes on the covered bridges were numerous. This led a contemporary writer to say: “Boys have lost a year’s growth by going through a covered bridge; girls have become gray before their time; stout farmers have had a queer feeling when the moon is high, the roads deserted, and the echoes of the horses’ hoofs are loud and strong.” The two main types of covered bridges were the lattice truss of wood and the Howe truss of iron and wood. One outstanding fact in connection with the old bridges is that they were not built by engineers or professional bridge-builders, but by local carpenters who put up the houses and barns in the adjacent countryside. This explains what has been termed their “homely simplicity.” They represented honest work. Those men had no knowledge of scientific building. Wind pressure and load limit were the first considerations. One builder constructed his bridges “high and wide as a load of hay.” That was his only specification. In commenting on the work of those covered bridge builders, a well-known engineer wrote: “Those early builders knew nothing of the theory of stresses; indeed many of them did not even call themselves engineers, but the long and honorable service of the structures they built, under loads far greater than the builders could have foreseen, is a striking testimonial to the excellence of the materials and the skilled workmanship that went into their construction.” A second striking fact in connection with the bridges is that the abutments were piled stone. The structure was held together by pegs of hard wood. No mortar, cement, bolts, or nails were used. The marvel is that so many of them have stood up for more than a century. In their way they were masterpieces of construction. A third feature of interest is that while most of the old bridges followed the same lines of construction, no two were precisely alike. Many writers have emphasized the fact that each bridge has a certain individuality. Nor was this individuality lacking in attractiveness. Some of the structures were architecturally beautiful with an old-time charm. [Illustration: On many a covered bridge it was a long way through and the trip was much more pleasant in the daytime than at night.] Crude as were the methods and materials employed, the old bridge builders left monuments to their skill. The bridge across the Schuylkill River near Philadelphia, built in 1813, had a span of 340 feet in length. When constructed, it was the longest span in the world. Another long bridge was at Charlemont, across the Deerfield River near the scene of the famous massacre of settlers by Indians in the early New England days. It was 324 feet long.