th Esk Bridge: "A less waterway might have sufficed, but _the valleys
may come to be meliorated by drainage_." One field drained after another
through all that confluence of vales, and we come to a time when they
shall precipitate, by so much a more copious and transient flood, as the
gush of the flowing drain-pipe is superior to the leakage of a peat.

It is plain there is here but a restricted use for formulas. In this
sort of practice, the engineer has need of some transcendental sense.
Smeaton, the pioneer, bade him obey his "feelings"; my father, that
"power of estimating obscure forces which supplies a coefficient of its
own to every rule." The rules must be everywhere indeed; but they must
everywhere be modified by this transcendental coefficient, everywhere
bent to the impression of the trained eye and the _feelings_ of the
engineer. A sentiment of physical laws and of the scale of nature,
which shall have been strong in the beginning and progressively
fortified by observation, must be his guide in the last recourse. I had
the most opportunity to observe my father. He would pass hours on the
beach, brooding over the waves, counting them, noting their least
deflection, noting when they broke. On Tweedside, or by Lyne or Manor,
we have spent together whole afternoons; to me, at the time, extremely
wearisome; to him, as I am now sorry to think, bitterly mortifying. The
river was to me a pretty and various spectacle; I could not see--I could
not be made to see--it otherwise. To my father it was a chequer-board of
lively forces, which he traced from pool to shallow with minute
appreciation and enduring interest. "That bank was being undercut," he
might say; "why? Suppose you were to put a groin out here, would not the
_filum fluminis_ be cast abruptly off across the channel? and where
would it impinge upon the other shore? and what would be the result? Or
suppose you were to blast that boulder, what would happen? Follow
it--use the eyes God has given you--can you not see that a great deal of
land would be reclaimed upon this side?" It was to me like school in
holidays; but to him, until I had worn him out with my invincible
triviality, a delight. Thus he pored over the engineer's voluminous
handy-book of nature; thus must, too, have pored my grandfather and
uncles.

But it is of the essence of this knowledge, or this knack of mind, to be
largely incommunicable. "It cannot be imparted to another," says my
father. The