The ornamental design for a fountain, as shown and described.
FIG. 1 is a front, top perspective view of my new design, the broken lines showing falling water located behind a viewing window, candles in candle holders located behind the falling water, and other ornamental, decorative features are for illustrative purposes only and do not form a part of the claimed design;
FIG. 2 is a front, top perspective view of my new design;
FIG. 3 is a top plan view of the design of FIG. 2;
FIG. 4 is a bottom plan view of the design of FIG. 2;
FIG. 5 is front elevation view of the design of FIG. 2;
FIG. 6 is a rear elevation view of the design of FIG. 2;
FIG. 7 is a right side elevation view of the design of FIG. 2; and,
FIG. 8 is a left side elevation view of the design of FIG. 2.
The broken lines in the figures are for illustrative purposes only and form no part of the claimed design. The rectangles in broken lines having long and short dashes illustrate locations of ornamental, decorative features that form no part of the claimed design.