In fall of 1970, Decometer readings were carried on simultaneously at four points, every 10 min. in daytime and 5 min. at night during 72 hours continuously. The consideration of selection of these points was made carefully in order to analysis data under uniformal propagation conditions. The constant deviations at each point and pattern were found respectively, but the correlation between the distance from the transmitter and the deviations could not ascertain clearly. Because the author considered that a large amount of deviation at each point might be introduced from the neighbouring interference on account of geological position. In the case of Red pattern, however, 3 points are positioned nearly on the great circle, and also, the deviation increased was proportionaly to the distance from the transmitter. The stability of Purple pattern is ±2-3 cel during, daylight, correspond to the distance in about 7-12m. To the contrary, from the transient time or so the Decometer readings will be oscillate gradually and progressed to night variation like the sine wave. These phenomenon are presumably introduced from the contamination of the skywave. Since the night variation is a large, the phenomea was caused by the variaton of the virtual height. The phenomena above could not analysed at the present time.
