Writing device for recorders, measuring instruments and the like

摘要

Recording or measuring equipment is provided with a spring clamp or clip for holding a replaceable writing unit by the ink reservoir of the writing unit. The reservoir carries a pen with a fiber or laminar tip and has a vent at or near the end shaped for insertion in the clamp or clip. A plug equipped with a gripping knob is inserted in the vent and the vent is so located that when the plug is so inserted, the ink reservoir cannot be inserted into and held by the clamp or clip, thus assuring that the vent is opened before the pen goes into use.