The ornamental design for a pair of spectacles, as shown and described.
FIG. 1 is a front elevational view of a pair of spectacles embodying my new design;
FIG. 2 is an elevational view of one side of the pair of spectacles, the opposite side thereof being of substantially the same appearance;
FIG. 3 is a top plan view thereof; and
FIG. 4 is a rear elevational view of the pair of spectacles with temples broken away for convenience of illustration.