In Baltimore it led to the misconceived construction of Fort Carroll, an island three-tiered brick fortification in the 1840s (similar to various other East Coast island forts built such as the famous Fort Sumter in Charleston harbor, South Carolina), supervised by young Col. Robert E. Lee of the United States Army Corps of Engineers but federal dredging appropriations preceded that project, beginning in 1830. This first project was completed in 1838. In the 1850s a second dredging project was undertaken, this time under Capt. Henry Brewerton, who was also later in charge of the Fort Carroll project. He excavated a straight channel from Sparrows Point out to the mouth of the Patapsco near Seven Foot Knoll Light between North Point and Hawkins Point, which was erected in 1855; this channel, known today as the Brewerton Channel, continues to be the central link in the path into the harbor. In 1865 Maj. William P. Craighill took over as Baltimore District Engineer of the Corps of Engineers. His initial survey of the Brewerton Channel disclosed severe shoaling at the mouth of the river, and he excavated a new channel starting from the older channel at a point just northwest of Seven Foot Knoll and running south to the mouth of the Magothy River, where it turned to the south-southeast and continued to Sandy Point, just north of the present location of the Chesapeake Bay Bridge. In the 1870s a cut-off channel was dug to ameliorate the turn between the old and new channels; the Brewerton Channel was also extended to provide a connection to the Chesapeake and Delaware Canal. Enlarged and extended to access various facilities within the port, the Brewerton and Craighill Channels continue in use to the present, essentially unaltered in configuration. Federal lighthouse construction in the bay began in the 1820s, and one early project was the erecting of range lights to guide ships into the Patapsco. These lights, the North Point Range Lights, were lit in 1822, marking a path roughly the same as that of the current Craighill Cutoff Channel. Subsequent channel construction was followed shortly by light projects. Brewerton's channel was marked by the Hawkins Point and Leading Point lights, constructed in 1868 and converted to skeleton towers in 1924. The original (lower) Craighill Channel was marked with range lights in 1875, following two years of temporary lightships; the cutoff was marked with the upper range lights in 1886, replacing the North Point range, which had been discontinued in 1873.