A grinding method is provided which can grind a processing surface of a workpiece by a blast processing without use of specific abrasives to obtain a glossy surface such as a mirror surface. The lower case includes a bottom surface disposed with two positioning holes formed separately from each other on a straight line orthogonal to a direction in which the tape cartridge is loaded into a drive device. The pressure in the controlled volume is reduced. The flow of liquid may be channeled with the inlet nozzle to flow in a second direction that is substantially perpendicular to the first direction. When the lower leg stands on a horizontal or inclined surface, the valve assembly is actuated by the lower leg to stop the operation of the hydraulic cylinder unit, thereby preventing rotation of the lower leg relative to the thigh. One of the irradiance incident on the at least one test specimen from the reflector device and the temperature of the at least one test specimen is adjustable by movement of selected mirrors from the first operative position to the second operative position in response to an input in order to control one of a temperature of the at least one test specimen or the irradiance.