[23 Aug. 1802]. Circumstances inducing him to leave the United States, King thinks it proper to commit to writing, his ideas on the subject of inland navigation, particularly the most proper situations and routes for canals. In Europe, the rise of manufactories has been the principal inducement to building canals. Where establishments are not near rivers, merchants have resorted to canals for the transport of bulky articles. The facility of this mode of conveyance, its safety, and its freedom from obstructions, other than frost, have given it a manifest advantage over river navigation, which, being subject to floods or scarcity of water, can occasion serious delays. It is more convenient and less expensive in many cases to make canals along the sides of navigable rivers than to remove impediments from those rivers. The United States should learn from Europe’s experience as to the “incompetency” of rivers above tidewater and direct their energies towards connecting the states by canals. Such canals should commence at tidewater, where river navigation begins to be inconvenient, then rise by locks to such height as to pass by the headwaters of lesser rivers and along the highest land upon which level pools could be maintained, thus providing connections between the principal rivers near the points of their origin. From there, canals might descend to tidewater again, between any other principal rivers whose sources are in that area. Canals might then extend into almost every part of the United States. King perceives many advantages to this system. Canals would be the shortest that the terrain permits. Those constructed beside or near rivers must either use expensive aqueducts to carry them over streams or runs that flow into the rivers, or wind around said runs, thus increasing the distance and expense. Canals upon the heights will frequently be circuitous but less so than those that follow rivers. Aqueduct bridges will not be necessary, and small runs of water that develop above the level of the canal can be “Moled” under the canal. The warping and filling up with silt from heavy rains is avoided. Distance from navigable rivers will prevent any interference with river navigations, and the facility with which vessels travel along the canals will give them the advantage. One might ask what will supply these canals with sufficient water. King answers that the highest mountains generally abound with springs, and that having designed a canal to pass along the lowest convenient part of a ridge, an engineer could collect water from springs of the land rising above. Also, reservoirs might be formed for carrying rain water. A series of these canals, connecting the principal rivers at the summit of the country and promoting trade, would “unite the general interests of the Inhabitants, and prove an indissoluble bond of Union.” Such canals would prove less expensive to maintain than carriage roads. Furthermore, at high ground, the soil is generally stronger and more “clayey,” thereby mitigating the many problems faced by canals at lower levels, where sides consisting of “made earth” are liable to leak and give way to water pressure. King now offers two potential examples. On the Virginia side of the Potomac, a canal might begin below Mason’s Island, rise by locks and pass the headwaters of the Occoquan, Thornton, Rapidan, and Rivanna Rivers, cross the mountains at the most convenient gaps, and then descend by the waters of the Kanawha or Guyandotte Rivers to the Ohio. Or it might pursue higher ground by the Holston River and enter the state of Kentucky. Such a canal deserves national support. Toll revenues would exceed the interest on the money advanced, and the canal would shift the trade of Kentucky from New Orleans to the District of Columbia. It would improve the bonds between the western and Atlantic states. Canal branches might also extend into Tennessee and other southern states. Another canal might be carried from Tyber Creek past the headwaters of the Monocacy and other streams flowing into the Potomac, across the Ohio, and then into the Northwest. The size and dimensions of these canals will be important. Some engineers prefer large canals, from 30 to 80 feet in width with a depth in proportion. The largest are proper for cutting through an isthmus, such as that between the Mediterranean and Red Seas. In inland navigations, canal widths seldom exceed 40 feet. Advocates for these larger canals tout the economies of scale yielded by large vessels, which will also have the benefit of excluding small, less responsible operators. Large canals inspire ideas of the greatness of the project while, by contrast, a small canal seems “a common ditch.” To avoid the latter impression, engineers will recommend larger canals so as to acquire reputation at the expense and risk of their employers. King points out the many disadvantages of pursuing large canals. First, the greater difficulty in cutting through and barrowing the earth increases costs. Large canals also require broader and deeper lock gates, which increase lock expenses. Such canals, which are often fordable, will need aqueducts and communication bridges. They make some smaller trades impractical, as the boats carry more cargo than a single client might have occasion to transport, thus forcing boats either to detain cargo or proceed with part of a load. Large canals are subject to greater waste of water through increased pressure on the canal, greater surface evaporation, and increased need to let out water for cleansing. Small canals have the following advantages. They cost less while bringing the same tolls, occasion fewer of the delays resulting from boats waiting for cargo, and require less expensive boats, making it more convenient for smaller proprietors to provide water carriage.