Abstract: A propulsion device comprises a water intake and a conduit for conveying water from the intake to an aperture. Apparatus is provided for forcing the water through the aperture in the form of a water jet as well as for subdividing the water into segments and accelerating each of the segments into the air. The method for propelling the nautical vessel comprises flowing water through a water intake in the vessel and conveying the water through a conduit from the intake to an aperture. The water is forced through the aperture in the form of a water jet and subdivided into segments which are accelerated into the air so as to provide a reaction force for propelling the nautical vessel.

Abstract: Apparatus for generating an animated image when viewed from a location in motion. The apparatus comprises a series of images; and at least one illumination device for emitting light flashes adapted to illuminate the images. Ignition devices are provided for causing a light flash to be emitted each time the location has moved a distance substantially equal to the spacing between two successive images. The illumination device is fixed relative to the images and is adapted to simultaneously illuminate an entire section including the series of images.A method of providing an animated image for viewing by a viewer at a location in motion relative to a series of stationary images. The method includes sensing the velocity of motion of the location relative to the series of images. A series of the images is illuminated for viewing from the location as the location moves past the images. The illumination device for flash illuminating the images is fixed relative to the images.

Abstract: An indicator for indicating the optimum angular position of a sail which is adapted to be rotated in various positions relative to a wind, and wherein the position of the sail may be represented by a polar curve comprising a laminar zone, a drop-off zone, a transition zone and a checking zone. The indicator comprises display means for displaying the optimum angular position of the sail relative to the wind as well as evaluation means for determining the position of the sail which corresponds to value between the end of the laminar zone and the beginning of the checking zone as a function of the direction of the wind. Means for indicating the direction of the wind to the evaluation means and driving means for driving the display means to display the optimum sail position are also included.

Abstract: An apparatus for measuring the density of a body which comprises: a main chamber adapted to receive the body whose density is to be measured; an auxiliary chamber; a subsonic wave generator for subjecting both of said chambers, in phase, to amplitude variations of pressure so as to generate subsonic waves; a differential manometer arranged between each of said chambers; means for equalizing the subsonic pressures of said two chambers; measurement means driven by said means for equalizing said subsonic pressures; and, weighing means for weighing said body, said weighing means being arranged within said main chamber.