FIG. 1 is a perspective view of a third rail support showing a first embodiment of my new design;
FIG. 2 is a left side elevational view thereof;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is a perspective view of a third rail support showing a second embodiment of my new design;
FIG. 9 is a left side elevational view thereof;
FIG. 10 is a right side elevational view thereof;
FIG. 11 is a front elevational view thereof;
FIG. 12 is a rear elevational view thereof;
FIG. 13 is a top plan view thereof; and,
FIG. 14 is a bottom plan view thereof.
The parts illustrated in dashed lines in FIGS. 1, 5-8 and 12-14 form no part of the claimed design.