Spherical Shape at www.japanese-home-gardens.com

Nearly all unlighted buoys are either a can buoy, which looks like a cylinder above water, or a nun buoy, which looks like a cone-topped cylinder above water. Some buoys are spherical in shape. In foreign waters, you may find a spar buoy, which looks a lot like a pile of wood floating upright. Lighted, sound, and combination (both light and sound) buoys exist in a variety of shapes; in such buoys, shape has no navigational significance.

Because the earth is essentially spherical, it is not possible to exactly portray the size and relationship of its various features on a flat surface. To get as good a match as possible, chart makers use various projections—graphical and mathematical methods of representing a spherical surface on a flat one—each of which has advantages and disadvantages. Boaters on the high seas and coastal waters will use charts using the Mercator projection

According to Helmholtz an increase in refractive power is due to an increase in the convexity of the lens surface. Gullstrand found, however, that this type of accommodation, which he termed "extracap-sular," accounts for only two thirds of the total accommodation achieved, while the other third is due to an "intracapsular accommodation" during which the internal elements of the lens assume a more spherical shape.