Editing Middlesex Canal (section)

===Construction===
The route of the canal was first surveyed in August 1793. Local lore is that it is on this expedition that Baldwin was introduced to [[Baldwin (apple)|a particular apple variety]] that now bears his name.  The route survey, however, was sufficiently uncertain that a second survey was made in October. Due to discrepancies in their results, Baldwin was authorized by the proprietors to travel to [[Philadelphia]] in an effort to secure the services of [[William Weston (engineer)|William Weston]], a British engineer working on several canal and turnpike projects in Pennsylvania under contract to the [[Schuylkill and Susquehanna Navigation Company]].<ref name="Kirby1935">Kirby, Richard Shelton. "William Weston and his contribution to early American engineering." Transactions of the Newcomen Society 16.1 (1935): 111-127.</ref><ref>Clarke, p. 25</ref> Baldwin's application to the Navigation company was successful: Weston was authorized to travel to Massachusetts. In July and August 1794, Weston, accompanied by Baldwin and several of the latter's sons surveyed and identified two possible routes for the proposed canal.<ref>Clarke, pp. 28-29</ref> The proprietors then secured contracts to acquire the land for the canal, some of which was donated by its owners; in sixteen cases the proprietors used [[eminent domain]] proceedings to take the land.<ref>Clarke, p. 35</ref>

[[File:Loammi baldwin.jpg|thumb|right|upright|Chief engineer [[Loammi Baldwin]]]]

The basic plan was for the canal's principal water source to be the [[Concord River]] at its highest point in [[North Billerica, Massachusetts|North Billerica]], with additional water to be drawn as needed from [[Horn Pond (Massachusetts)|Horn Pond]] in Woburn. The site where the canal met the Concord River had been the site of a grist mill since the 17th century, which the proprietors purchased along with all of its water rights. From this point, the canal descended six miles to the Merrimack River in East Chelmsford (now western [[Lowell, Massachusetts|Lowell]]) and 22 miles to the Charles River in Charlestown.

In late September 1794 ground was broken in North Billerica. Work on the canal was performed by a number of contractors. In some instances, local workers were contracted to dig sections, while in other areas contract labor was brought in from Massachusetts and New Hampshire for the construction work. A variety of engineering challenges were overcome, leading to innovations in construction materials and equipment. A form of [[hydraulic cement]] (made in part from volcanic materials imported at great expense from [[Sint Eustatius]] in the West Indies) was used to make the stone locks watertight. Because of its cost and the cost of working in stone, a number of the locks were made of wood instead. An innovation was made in earth-moving equipment with the development of a precursor of the [[dump truck]], where one side of the carrier was hinged to allow the rapid dumping of material at the desired location.

Water was diverted into the canal in December 1800, and by 1803 the canal was filled to Charlestown. The first boat operated on part of the canal on April 22, 1802.