In 1960 I suggested that Deception Island, near the northern end of the Antarctic Peninsula, might serve as a useful naturally resonant VLF slot antenna. Connection across the island was subsequently made and impedance measurements were obtained. Contrary to theoretical predictions by Galejs and by Staras, a strong resonance was obtained. However, it occurred at 9.5 kHz, rather than at 5 kHz as anticipated. This is ascribed to a short, low cut through one of the arms of the island which otherwise range from 500 to 1000 ft high. A composite transmission line model is constructed to represent the data. A first approximation to the efficiency suggests that it is in the range of

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Whistler‐derived electron densities in the equatorial plane have been compared with the plasmapause position as determined by the Explorer 45 double‐probe experiment during times of relatively quiet magnetic activity. From periods where good coincidence of the data was obtained, the double‐probe data saturation point (indicating the plasmapause) is estimated to have been in the vicinity of 60 el/cm³. By using this comparison the dayside plasmasphere was monitored over a 20‐hour period on July 21 and 22, 1972, with two widely spaced whistler ground stations and Explorer 45. Irregularities in the dayside plasmasphere which appeared to be enhanced by dayside processes involving magnetic activity and/or micropulsations were seen during a small disturbance centered in this very quiet period.