Just before it reaches the falls in Billerica, it is contracted, and becomes swifter and shallower, with a yellow pebbly bottom, hardly passable for a canal-boat, leaving the broader and more stagnant portion above like a lake among the hills. All through the Concord, Bedford, and Billerica meadows we had heard no murmur from its stream, except where some tributary runnel tumbled in,--

Some tumultuous little rill,
Purling round its storied pebble,
Tinkling to the selfsame tune,
From September until June,
Which no drought doth e'er enfeeble.

Silent flows the parent stream,
And if rocks do lie below,
Smothers with her waves the din,
As it were a youthful sin,
Just as still, and just as slow.

But now at length we heard this staid and primitive river rushing to her fall, like any rill. We here left its channel, just above the Billerica Falls, and entered the canal, which runs, or rather is conducted, six miles through the woods to the Merrimack, at Middlesex, and as we did not care to loiter in this part of our voyage, while one ran along the tow-path drawing the boat by a cord, the other kept it off the shore with a pole, so that we accomplished the whole distance in little more than an hour. This canal, which is the oldest in the country, and has even an antique look beside the more modern railroads, is fed by the Concord, so that we were still floating on its familiar waters. It is so much water which the river _lets_ for the advantage of commerce. There appeared some want of harmony in its scenery, since it was not of equal date with the woods and meadows through which it is led, and we missed the conciliatory influence of time on land and water; but in the lapse of ages, Nature will recover and indemnify herself, and gradually plant fit shrubs and flowers along its borders. Already the kingfisher sat upon a pine over the water, and the bream and pickerel swam below. Thus all works pass directly out of the hands of the architect into the hands of Nature, to be perfected.

It was a retired and pleasant route, without houses or travellers, except some young men who were lounging upon a bridge in Chelmsford, who leaned impudently over the rails to pry into our concerns, but we caught the eye of the most forward, and looked at him till he was visibly discomfited. Not that there was any peculiar efficacy in our look, but rather a sense of shame left in him which disarmed him.

It is a very true and expressive phrase, "He looked daggers at me," for the first pattern and prototype of all daggers must have been a glance of the eye. First, there was the glance of Jove's eye, then his fiery bolt, then, the material gradually hardening, tridents, spears, javelins, and finally, for the convenience of private men, daggers, krisses, and so forth, were invented. It is wonderful how we get about the streets without being wounded by these delicate and glancing weapons, a man can so nimbly whip out his rapier, or without being noticed carry it unsheathed. Yet it is rare that one gets seriously looked at.

As we passed under the last bridge over the canal, just before reaching the Merrimack, the people coming out of church paused to look at us from above, and apparently, so strong is custom, indulged in some heathenish comparisons; but we were the truest observers of this sunny day.