The ornamental design for a "solar heater," substantially as shown and described.
FIG. 1 is a perspective view of the top of a "solar heater" including a
downwardly depending flexible skirt according to our design;
FIG. 2 is a perspective view of the underside of the design with the
downwardly depending flexible skirt shown in a different position for
purposes of illustration; and
FIG. 3 is a sectional view on a slightly enlarged scale similar to FIG. 2,
the plane of the section being indicated by line 3--3 in FIG. 2.