Dams Made the Lehigh Canal

Dams Made the Lehigh Canal. "It should be borne in mind that in timber dams it is the weight of the stone ballast that keeps the structure in place, and not the bulk and combination of the timbers." , Edwin F. Smith, Dam Building in Navigable and Other Streams (Engineers Club of Philadelphia), 1888., Dams were an essential part of the Lehigh Navigation, the river-and-canal waterway completed in 1829 that carried boats loaded with anthracite from Carbon County's mines to Easton and beyond. The dams had two functions: they created "slackwater pools" where the river was deep and slow enough to move mule-drawn boats along its banks. The dams also fed water into the canal ditches and ensured that the Lehigh Canal never ran dry., The nine dams were numbered; Dam No. 1 was about 10 yards upstream of the new Mansion House Pedestrian Bridge. Dam No. 1 was a wing dam; instead of stretching all the way across the river, it had a long arm, or "wing" that extended upstream on the eastern side. The wing allowed the canal boats to maneuver safely from the coal loading chutes upstream, through Lock 1 and into the canal. The entrance to Lock 1, also known as Guard Lock 1, has been partially stabilized, and is adjacent to the eastern end of the Bridge., The dams in the Lehigh River were built using the standard technology of the time. Large timbers were stacked, similar to the walls of log cabins, and the interior boxes were filled with stones. These were called "cribs," and the dams "crib dams." The foundation of the wing of Dam 1 was uncovered during excavation for the Mansion House Bridge. In order to proceed with construction the timber "cribs" were removed and the logs that remained whole were stacked on site. Laboratory analysis revealed that these timbers are mostly hemlock trees from central Pennsylvania and the oldest of the samples began growing around 1547.