We claim the ornamental design for a microscope, as shown and described.
FIG. 1 is a front perspective view of a microscope.
FIG. 2 is a right side elevational view thereof.
FIG. 3 is a left side elevational view thereof.
FIG. 4 is a front elevational view thereof.
FIG. 5 is a rear elevational view thereof; and,
FIG. 6 is a top plan view thereof.
The broken lines shown represent unclaimed subject matter and form no part of the claimed design. The bottom side of the microscope forms no part of the claimed design.