Novel hydroxamic acid derivatives, e. A thermally foaming adhesive layer of the adhesive sheet 12 functions as a shock absorber, whereby the wafer 11 hardly cracks during a high-speed grinding operation even if the wafer uses a GaAs substrate which is susceptible to damages. Lubrication of the horizontally oriented engine distributes the oil into a space within the cylinder surrounding the middle of the dual-piston. The device can be held with one hand while the various components are placed one by one into their proper position onto the rod, leaving the other hand free to manipulate the other components. The connector includes two positioning parts which abut against the respective frame members and to be connected to position the frame members in a respective longitudinal direction thereof, and the frame members and includes a part to be positioned which abuts against the positioning part of the connector, and coupling means and are formed to couple the frame members and with the connector.