When the wind acts on the surface of the sea it drives before it the particles of the surface layer of water, and, as these cannot be parted from those immediately beneath, the internal friction of the fluid causes the propelling impulse to act through a considerable depth, and if the wind continued long enough it would ultimately set the whole mass of the ocean in motion 'right down to the bottom.
The oblique line referred to as running diagonally across the wing virtually divides the wing into an active and a passive part, the former elevating and propelling, the latter sustaining.
Pelagic organisms, floating on the surface of the open sea, propelling themselves feebly by the pumping movements of the umbrella produced by contraction of the sub-umbral musculature, and capturing their prey with their tentacles.
One of these problems, illustrated by experiment, deals with an ingenious mode of propelling vessels by the reaction of water ejected from the stern.
Of the energy exerted by the powder in exploding will be employed in propelling the ball, and ih in producing the recoil of the gun, provided the gun up to the instant of the balls quitting the muzzle meets with no resistance to its recoil except the friction of the ball.
In this instance a very slight movement at the root of the pinion, or that end of the lever directed towards the body, 1 is followed by an immense sweep of the extremity of the wing, where its elevating and propelling power is greatest - this arrangement ensuring that the large quantity of air necessary for support and propulsion shall be compressed under the most favourable conditions.
A, Large aeroplane; b, Small aeroplane; c, Propelling screws.