FIG. 1 is a front, right, top perspective view of a horizontal prism bar showing my new design;
FIG. 2 is a front, right, bottom perspective view thereof;
FIG. 3 is a front, left, top perspective view thereof;
FIG. 4 is a back, left, top perspective view thereof;
FIG. 5 is a front elevational view thereof;
FIG. 6 is a rear elevational view thereof;
FIG. 7 is a left side elevational view thereof;
FIG. 8 is a right side elevational view thereof;
FIG. 9 is a bottom plan view thereof; and,
FIG. 10 is a top plan view thereof.
The broken lines shown portion of the article which form no part of the claimed design.