"Design work was completed and construction initiated on a prototype field altimeter based on the gas density dependence of Townsend discharge current in an electrical discharge. The design of an ion tracer air velocity meter for laboratory applications, and construction of three units were successfully completed. Theoretical and experimental support is presented, showing the applicability of the ion tracer system to the accurate measurement of linear gas velocity. The operating range of the laboratory meter is 150 to 2500 ft/min at ambient pressures between 200 mu and 30.0 mm Hg. Further investigations on the application of the ion tracer concept to flowrate measurements are presented. By generating velocity profile curves with an ion tracer calibrated thermoanemometer, it was possible to determine the flowrate for 2 flow and pressure conditions; 37.5 cfm at 19.6 mm and 75 cfm at 9.8 mm Hg. Comparison with a calibrated Rotameter technique was within 5% in both cases. Also presented are some preliminary investigations leading to the development of a generalized ion tracer flowmeter for low gas densities. Results of some supplemental electrical discharge experiments in rarefied atmospheres are described. It was observed that electrical oscillations could be produced in a low density gas discharge, …