158 



ATMOSPHERICAL ELECTRICITY. 



[1854. 



same average fund of electricity always. There is no proof that 

 it ever borrows electricity of foreign orbs or makes to them a 

 loan of its own. The phenomena under consideration are purely 

 meteorological, and not cosmical. It is by a change in the dis- 

 tribution of this normal quantity of electricity that one part of 

 the planet acquires an excess while another is deficient. But it 

 is not so easy to prove by direct experiment that the earth is 

 negatively charged, as to draw down and handle the positive 

 electricity of the clouds. The unequal amount of evaporation in 

 different parts of the earth's surface, and a partial distribution of 

 moist winds, will produce charges of electricity in the air much 

 larger at some places than at others, and the imperfect conducting 

 power of the air will be unfavourable to a speedy equalization. 

 On this account the electricity of the air will be in a large sense 

 of a local character. The opposite and corresponding charge of 

 the solid earth will more easily spread over its whole surface. 

 With the ample range thus afforded to its own inherent diffu- 

 siveness, it will retain only a feeble power at any one place. It 

 is not surprising, therefore, that the electrical charge of the solid 

 earth is rarely recognized by the senses. Sometimes, and in 

 some places, geographical locality may be opposed to an imme- 

 diate diffusion of the electricity, .so that if the exciting cause is 

 active, a sufficient charge may accumulate to attract attention. 

 In such cases, the electricity, following so far as it can spread 

 the usual laws of distribution, will concentrate its forces around 

 the sharp peaks of mountain-tops, which are the natural and ap- 

 pointed dischargers to the planet. Hence positive clouds are 

 seen to congregate as if by electrical attraction around the pin- 

 nacled battery of the earth. The electricity of the earth shows 

 itself, if at all, by a brush or star of light on pointed objects 

 resting on the earth, and projecting into the air. The records 

 of these displays have accumulated with years, and are found in 

 the literature and common language of every age and country. 

 The. ancients distinguished them by the name of Castor and 

 Pollux. In modern times, and around the shores of the Medi- 

 terranean, they are hailed as the light of St. Clare, St. Nicolas, 

 St. Helena, and elsewhere they bear the appellation of St. Barbe 

 or St. Elmo. The Portuguese call them Curpo Santo, and the 

 English, Comazants. These lambent flames, as they appear, 

 have been seen blazing from the summits of the Himalaya and 

 Cordillera mountains. They are frequently seen tipping with 

 fire the masts and spars of ships. We are told that in the 

 voyage of Columbus, as soon as St. Elmo appeared with his 

 wax tapers, the sailors began to sing, thinking that the storm 

 was over. The electricity of the earth while in the act of dis- 

 charging itself into the air has been seen edoino- with lioht the 

 manes of horses, the metal trimmings of their harness, the lashes 

 ot whips, the brims of hats, the tops and edges of umbrellas, the 

 sharp points of swords and lances, the extremities of hair and 

 whiskers, the corners of chapeaux, the buttons upon the coat, 

 filaments of straw, the beaks of birds, and the myriad needle-like 

 terminations of vegetable growth, with that incomparable point 

 and finish which they took from Nature's own hands. In 1778 

 these electrical brushes embellished the crosses upon the steeples 

 in Rouen, as well as other points of eminence. At the siege of 

 Kingsall, in 1601, the sentinel saw electrical tapers burning on 

 the points of lances and swords. Guyan says, that they are 

 often noticed on the bayonets of the soldiers at Fort Gowrava, 

 Bougie, 2200 feet above the level of the sea. During a thunder- 

 storm they have appeared like the work of. induction, gleaming 

 upon the points of the fire-arms in the armory of the Tower of 

 London. In Poland, Captain Bourdet was astonished to see, in 

 December, 1806, the electrical glow upon the ears of the horses, 

 on the metallic knobs of their harness, and on the whiskers of 

 the troops. On the 25th of January, 1S22, the tops of the trees 



at Freyburg were touched with light during a snow-storm. In 



1824, a load of straw became animated and danced the electrical 

 hop, each straw standing on end, and shining at the top. In 



1825, Sir William Hooker and a party of botanists who were 

 upon Ben Nevis, shed the electrical light from their hair when 

 they lifted their hats. In May, 1831, the hair of the officers at 

 Algiers stood erect, decked out with fire. Walker, the English 

 electrician, on the 8th of September, 1842, saw the same light 

 on the top of his own lightning-rod. On the 17th of January, 

 1817, an extensive snow-storm was experienced in Maine, Ver- 

 mont, Massachusetts, and even in Pennsylvania and Georgia. 

 Professor Cleaveland says, that upon this occasion three persons, 

 crossing the bridge over the Androscoggin, observed the borders 

 of their hats to be luminous, and the ends of their fingers, though 

 covered with gloves, were radiant with light. Professor Dewey 

 of Williimstown relates, that upon the same occasion a physician 

 saw the light upon the ears and hair of his horse. A gentleman 

 tried to brush it from his hat, thus reminding one of the sailor 

 who was sent to the top-mast to bring the fire of St. Elmo down. 

 In both cases the experiment was attended with the same success. 

 The light spread more widely for being disturbed. Other 

 persons witnessed the same brightness on the trees, fences, and 

 logs. It was reported that a hiss was heard when the hand was 

 presented to these objects. Moreover, the lightning was frequent. 

 A young man in Vermont described the phenomenon after this 

 wise. It appeared as a star or spark oftener than as a brush. A 

 sound could be heard at the distance of six or eight feet resem- 

 bling that of water in a tea-kettle just before it boils. The effect 

 was greater on high ground than on low, so that the light was 

 then seen on the hat and shoulders. The brush was sometimes 

 two inches in length, and three quarters of an inch in diameter. 

 To spit was to emit from the mouth a luminous stream of fire. 

 At Shelburn, Massachusetts, a similar light was seen upon a 

 well-pole : when the end came down the light disappeared, and 

 was kindled again when it went up. Arago mentions other 

 cases where the spit was luminous, and one at least has come 

 within my personal observation at Cambridge. In 1767, Tupper 

 and Lanfiar observed near Mount Etna, that by moving their 

 hands through the snowy air they produced sounds which could 

 be heard at the distance of forty feet. In 1781, Saussure, the 

 great Alpine observer, fell a cobweb sensation among his fingers, 

 and his attendants were able to draw sparks from a gold button 

 on his chapeau. The beaks of birds have appeared luminous 

 during storms, and it has been suggested that the eagle by some 

 preeminence in this respect acquired its cognomen of the minister 

 of the thunder-bolt. We may introduce here an experience of 

 Sabine and James C. Ross, during an arctic voyage, as indicating 

 possibly the electrical condition of the earth or air. They 

 entered a luminous track, about four hundred metres long, and 

 while in it they could see the tops of their masts, the sails and 

 cordage of their ship, and when they left it they passed suddenly 

 into outer darkness. 



Arago has collected, with amazing industry, passages from the 

 classics which may possibly contain allusions to the electrical 

 light. Thus Cffisar, in the African War, says that the lances of 

 the fifth legion seemed on fire during a night of hail-storms. 

 Livy states, that the javelin of Lucius Atreus cast forth flames 

 for two hours without being consumed. Plutarch records the 

 fact, that when the fleet of Lysander was on the point of attacking 

 the Athenians, Castor and Pollux arose and stood on the two 

 sides of the galley of the Lacedemonian admiral. He refers to 

 similar observations in Sardinia and Sicily. Pliny had seen just 

 such lights on the points of the soldiers' pikes. Seneca alludes 

 to a star which reposed on the iron part of the lance of Gylippus, 



