the service
of the engineer. "The very term mensuration sounds _engineer-like_," I
find him writing; and in truth what the engineer most properly deals
with is that which can be measured, weighed, and numbered. The time of
any operation in hours and minutes, its cost in pounds, shillings, and
pence, the strain upon a given point in foot-pounds--these are his
conquests, with which he must continually furnish his mind, and which,
after he has acquired them, he must continually apply and exercise. They
must be not only entries in note-books, to be hurriedly consulted; in
the actor's phrase, he must be _stale_ in them; in a word of my
grandfather's, they must be "fixed in the mind like the ten fingers and
ten toes."

These are the certainties of the engineer; so far he finds a solid
footing and clear views. But the province of formulas and constants is
restricted. Even the mechanical engineer comes at last to an end of his
figures, and must stand up, a practical man, face to face with the
discrepancies of nature and the hiatuses of theory. After the machine is
finished, and the steam turned on, the next is to drive it; and
experience and an exquisite sympathy must teach him where a weight
should be applied or a nut loosened. With the civil engineer, more
properly so called (if anything can be proper with this awkward
coinage), the obligation starts with the beginning. He is always the
practical man. The rains, the winds and the waves, the complexity and
the fitfulness of nature, are always before him. He has to deal with the
unpredictable, with those forces (in Smeaton's phrase) that "are subject
to no calculation"; and still he must predict, still calculate them, at
his peril. His work is not yet in being, and he must foresee its
influence: how it shall deflect the tide, exaggerate the waves, dam back
the rain-water, or attract the thunderbolt. He visits a piece of
sea-board: and from the inclination and soil of the beach, from the
weeds and shell-fish, from the configuration of the coast and the depth
of soundings outside, he must deduce what magnitude of waves is to be
looked for. He visits a river, its summer water babbling on shallows;
and he must not only read, in a thousand indications, the measure of
winter freshets, but be able to predict the violence of occasional great
floods. Nay, and more: he must not only consider that which is, but that
which may be. Thus I find my grandfather writing, in a report on the
Nor