In two flights of a parachute-borne Gerdien probe (May 15, 1968, and June 7, 1975) good agreement of mobility values has been found for the height range (60--30 km not only between the results of the two flights but also with the values reported by Conley (1974). The same holds for the conductivity measurements, except that the ledge of the increase of conductivity was found to start at 44 km in the 1975 flight in contrast to 66 km as was seen in the 1968 data. Some conceivable causes for this height variation are discussed qualitatively. Good agreement was found with conductivity data reported by Hale (1968, 1974).