364 SCIENTIFIC RECORD FOR 1884. 



341. Lieutenant Lephay, with a Mascart self-register and a water- 

 dropping collector 3 meters above tbe earth's surface and 24 meters 

 above the ocean, at the French international station at Cape Horn, de- 

 duces the following results as to atmospheric electricity: 



1. The normal tension is positive and between 50 and 70 volts; its 

 maximum occurs in clear sky and frosty weather. 



2. The daily maxima and minima ordinarily observed were only ap- 

 parent at the cape in beautiful weather, with clear, blue skies free of 

 clouds. 



3. Whenever the sky is beclouded after a fine day the normal ten- 

 sion immediately changes, and vice versa when the cloudiness clears 

 away. 



4. Clouds affect the electrometer in different ways, according to the 

 form of the i)recipitated water, and even according to their direction 

 from the observatory; cumuli increase the positive tension; high cirro- 

 cumuli increase it still further to plus 400 volts ; cirro stratus seem to 

 have no influence; fog and fine rain produce a positive tension that is 

 sometimes very high. 



5. With hail there always comes an extraordinary strong, negative 

 tension, so that even sparks dart from the upper part of the apparatus. 



6. Snow gives always a positive tension, and by so much the greater 

 as the snowfiakes are larger, 



7. Eain, with four exce])tious, always gave a negative tension. 



8. A fall of snow-dust and small ice-crystals on the 8th of May oc- 

 curred with a decided positive tension. 



9. Of three sleet storms, two occurred with foggy weather, fine rain, 

 and positive tension, and one with heavy rain and negative tension. 



10. For twelve or fifteen hours before the outbreak of heavy winds 

 and gusts the positive tension increased. It is not possible to say what 

 tension prevails during the storm itself, since the rapid-psissing clouds 

 obscure the influence of the winds by their own more ])o\verful eflect. 

 The dry, warm, north-northwest or northeast winds diminish the posi- 

 tive or increase the negative tension; tlie cold west, southwest, and 

 south-southwest winds increase the positive tension. The strongest 

 electric phenomena occurred with moist winds from the west northwest 

 and west southwest. [Z. 0. O. ill., xix, p. 471.) 



342. Prof E. Mach has more accurately investigated the amount of 

 protection from a lightning discharge, as actually experienced by an ob- 

 ject inside of a metal box representing the wire-cage inclosure in Mel- 

 sen's system of protection from lightning. He finds that although the 

 theoretical explanation of Melsen's system must be slightly modified, 

 still even when the wire of the cage is brought to a red heat by the 

 lightning discharge the interior will be almost perfectly protected. {Z. 

 0. G. ilf, XIX, p. 264.) 



343. Prof. J. J. Spartsch, of Breslau, in an essay on tlie climatology 

 of Greece, states that the statistics of the thunder-storms, or of days on 



