100 YEARS AGO

Dr. Sven Hedin, the Swedish explorer, who recently arrived at Ladakh from Central Asia, has sent a telegram to King Oscar announcing that he has made an extremely important journey through all Tibet, disguised as a pilgrim, with two followers. On approaching Lhasa they were recognised and captured, but were well treated by order of the Dalai Lama. A second attempt was opposed by 500 Tibetan soldiers. Dr. Hedin's collections were lost, with almost the whole caravan, but his notes were saved.

From observations described by Prof. Geitel in the Physikalische Zeitschrift, iii. 4, it appears that atmospheric air is itself capable of inducing radio-activity. When a mass of air remains shut up for a long time in a cellar or a cave, Prof. Geitel finds that its electric conductivity increases to a maximum. There are three hypotheses possible, namely, that the exposed substances were themselves radio-active, that traces of radio-active substances were present in the neighbourhood, or that the air itself is the origin of the radio-activity... Prof. Geitel favours the view that the third is the most likely hypothesis.

Many animals have popular names which have been derived from their cries. Prof. T. D. A. Cockerell writes to suggest that this is also the case with the donkey, the “don” representing the inspiratory and “key” the expiratory sound. Most dictionaries describe the word, which is of comparatively recent origin, as signifying a little dun animal, from dun and the diminutive term — key, but the grounds upon which this derivation is based are not easy to find.

From Nature 2 January 1902.

50 YEARS AGO

On September 29, 1951, Dr. Seth B. Nicholson, while examining a plate exposed earlier that night, discovered an object which he thought was a new satellite of Jupiter. No announcement was made until the object had been photographed later on three occasions with the 60-in. telescope at Mount Wilson and also with the 100-in., with which Dr. Nicholson had made the first photograph... The magnitude of the new satellite is 18.3, but this is only a provisional figure; its diameter has been estimated to be about 15 miles — the diameter of satellite X. Dr. Nicholson now ranks with Galileo as the only astronomer who has discovered four of Jupiter's satellites.

From Nature 5 January 1952.