Henry and John Thoreau took themselves on a two-week boat trip up the Concord and Merrimack Rivers at the end of the summer in 1839. Henry wrote a book about their adventure, A Week on the Concord and Merrimack Rivers, published in 1849; he paid for it to be published because no Boston or New York publisher would take the book. Here’s Henry’s account of arriving at the Merrimack, from the first draft of the manuscript, taken from Thoreau’s Complex Weave: The Writing of A Week on the Concord and Merrimack Rivers, edited by Linck C. Johnson (University Press of Virginia, 1986):

By noon we were let down into the Merrimack through the locks at Middlesex, just above Pawtucket Falls, after having rested ourselves under some oaks on the bank of the canal in Chelmsford, and caught a few bream for our dinner. We shall not soon forget the humane man at the locks—so serene & liberal in alliance with god and nature—noiselessly met—and without noise understood—a lover of the higher mathematics as we found—& in the middle of a vast sunny problem when we overtook him, and whispered our own conjectures—one of the race of—who will surely find the grand Shekinah at last—who over stepped his prescribed duty and helped us through the locks discerning through our disguise that we were breaking no law of Gods that sunday.

1801 map of Middlesex Canal at Merrimack River (web image courtesy of lowelllandtrust.org)