St Elmo's Fire.-Luminous discharges from masts, lightning conductors, and other pointed objects are not very infrequent, especially during thunderstorms. On the Sonnblick, where the phenomenon is common, Elster and Geitel (87) have found St Elmo's fire to answer to a discharge sometimes of positive sometimes of negative electricity.
This was confirmed by Elster and Geitel (7), whose form of dissipation apparatus has been employed in most recent work.
For a wire exposed under the conditions observed by Elster and Geitel the emanation seems to be almost entirely derived from radium.
Lenard, Elster and Geitel, and others have found the potential gradient negative near waterfalls, the influence sometimes extending to a considerable distance.
This last result of course is favourable to Elster and Geitel's views as to the source of the emanation.
In 1901 Elster and Geitel found that a radioactive emanation is present in the atmosphere.
In the earliest times Lower Lusatia reached from the Black Elster to the Spree; its inhabitants, the Lusitzi, were conquered by the German king, Henry the Fowler, and by the margrave Gero in the 10th century.
The Elster and Geitel apparatus is furnished with a cover, serving to protect the dissipator from the direct action of rain, wind or sunlight.
Annual and Diurnal Variations.-At Wolfenbi ttel, Elster and Geitel found A vary but little with the season.
It took Blucher time to extricate his troops from the confusion into which the battle had thrown them, and the garrison of Leipzig and the troops left on the right bank of the Elster still resisted obstinately - hence no direct pursuit could be initiated and the French, still upwards of 10o,000 strong, marching rapidly, soon gained distance enough to be reformed.