26 APPARATUS AND INSTRUMENTS FOR MEASURING, CONTROLLING AND MONITORING FORCE, PATH PRESSURE AND VELOCITY IN PRESSURE DIE-CASTING AND INJECTION MOULDING MACHINES, INCLUDING APPARATUS AND INSTRUMENTS FOR MEASURING THE VELOCITY OF MOVING PARTS IN PRESSURE DIECASTING MACHINES AND INJECTION MOULDING MACHINES-NAMELY, FOR MEASURING THE VELOCITY OF THE DIE-CASTING OR INJECTION PLUNGER