where the muskrat houses line the shores, or what was the shore, some three feet high, and regularly sharp, as the Peak of Teneriffe. C. says, "Let us land; 'the angle of incidence should be equal to the angle of reflection.'" We did so. By the island where I formerly camped, half a mile or more above the bridge on the road from Chelmsford to Bedford, we saw a mink, slender, black at ten rods distance (Emmonds says they are a dark, glossy brown), very like a weasel in form. He alternately ran along the ice and swam in the water, now and then holding up his head and long neck, and looking at us,—not so shy as a muskrat; I should say very black. The muskrats would curl up into a ball on the ice, decidedly reddish brown. The ice made no show, being thin and dark. The mink's head is larger in proportion to the body than the muskrat's, not so sharp and rat-like. Left our boat just above the last-named bridge on west side. A bright, dazzling sheen for miles on the river as you look up it. Crossed the bridge, turned into a path on the left, and ascended a hill a mile and a half off, between us and Billerica, somewhat off from the river. The Concord affords the water prospects of a larger river, like the Connecticut even, hereabouts. I found a spear-head by a mysterious little building. On the west side of the river in Billerica
