y. It is hardly proper, perhaps, to call this resistance by the name
of friction; it is partly, perhaps mainly, due to the viscidity or adhesion
of the water.

539. _Q._--Perhaps at high velocities this resistance may become less?

_A_.--That appears very probable. It may happen that at high velocities the
adhesion is overcome, so that the water is dragged off the vessel, and the
friction thereafter follows the law which obtains in the case of solid
bodies. But any such conclusion is mere speculation, since no experiments
illustrative of this question have yet been made.

540. _Q._--Will a vessel experience more resistance in moving in salt water
than in moving in fresh?

_A._--If the immersion be the same in both cases a vessel will experience
more resistance in moving in salt water than in moving in fresh, on account
of the greater density of salt water; but as the notation is proportionably
greater in the salt water the resistance will be the same with the same
weight carried.

541. _Q._--Discarding for the present the subject of friction, and looking
merely to the question of bow and stern resistance, in what manner should
the hull of a vessel be formed so as to make these resistances a minimum?

_A._--The hull should be so formed that the water, instead of being away
driven forcibly from the bow, is opened gradually, so that every particle
of water may be moved aside slowly at first, and then faster, like the ball
of a pendulum, until it reaches the position of the midship frame, at which
point it will have come to a state of rest, and then again, like a
returning pendulum, vibrate back in the same way, until it comes to rest at
the stern. It is not difficult to describe mechanically the line which the
water should pursue. If an endless web of paper be put into uniform motion,
and a pendulum carrying a pencil or brush be hung in front of it, then such
pendulum will trace on the paper the proper water line of the ship, or the
line which the water should pursue in order that no power may be lost
except that which is lost in friction. It is found, however, in practice,
that vessels formed with water lines on this principle are not much
superior to ordinary vessels in the facility with which they pass through
the water: and this points to the conclusion that in ordinary vessels of
good form, the amount of power consumed in overcoming the resistance due to
the wave at the bow and the partial vacuity at the stern is