Abstract: A dissolved oxygen analyzer which includes a sensor having a lead electrode and lead wire extending therefrom and a silver electrode and silver wire extending therefrom. The electrodes are immersed in an electrolyte and both metals are substantially pure. The silver electrode is positioned in adjoining relationship to an oxygen permeable membrane immersed in a sample water stream being tested. The sensor further includes a pressure equalizing diaphragm in communication with the sample water to maintain uniformity of pressure in the sensor with that of the water and a constant head tank maintains uniform water pressure and a thermistor monitors the water temperature and modifies the output of an amplifier connected to said wires to compensate for temperature changes.

Abstract: Electrocardiographic apparatus wherein said apparatus is contained within a wholly insulated enclosure and the recording assembly including writing pens is provided with means for placing an insulating barrier in a position to protect the pens when replenishing the recording paper.