122 



NOTES TO PRECEDING SECTION. 



experienced Portuguese pilot, taught that there •were four 

 lines witliout variation. This view appears, if we may 

 judge from the controversy of Henry Bond (author of the 

 worlc — The Longitude Found, 1676) with Beckborrow, to 

 have had some influence upon Ilalley's Theory of magnetic 

 poles. Vide my Examen critique de I'hist. de la Geo- 

 graphie, t. iii. p. 60. 



139 (p. 58.)— Halley, in the Philosophical Transactions, 

 vol. xxix. (for 1714—1716, No. 341). 



140 (p. 58.)— Dove, in Poggendorff's Annalen, Bd. xx. S. 

 341, Bd. xix. S. 388: "The dipping needle comports itself 

 veiy nearly as an atmospherical thermometer, whose differ- 

 ence in like manner shows the increased tension of the 

 electricity before this has risen to such a height that a 

 spark is elicited. Vide also the excellent observations of 

 Prof. Kaemtz, in his Lehrbuch der Meteorologie, Bd. iii. S. 

 511—519; Sir David Brewster, Treatise on Magnetism, p. 

 280. On the magnetic properties of the galvanic flame or 

 luminous bow from a Bunsen's charcoal and zinc battery, 

 vide Casselmann's Beob. (Marburg, 1844,) S. 56—62. 



l'*i (p. 59.)— Argelander's important observations on the 

 Northern Lights, embodied in his Vortrage, srehalten in der 

 physikahsch-okononiischcn Gesellschaft zu KBnigsberg, Bd. 

 i. 1834, S. 257—264. 



I4i2 (p. 59.) — On the results of the observations of Lottin, 

 Bravais, and Siljerstrom, who passed a winter at Bosekop, 

 on the coast of Lapland (70° N. Lat.), and in 210 nights 

 saw 160 Aurorae boreales, vide Comptes rend us de I'Acad. 

 des Sciences, torn. x. p. 289, and Martin's Meteorologie, 

 1843, p. 453. See also Argelander, in his Vortrftge, geh. 

 in der Konigsberg. Gesellschaft, Bd. i. S 259. 



l*i (p. 59.)— John Franklin (Narrative of a Joumev to 

 the Shores of the Polar Sea in the years 1819—1822, p.' 552 

 and 597; Thienernann,in Edinburgh Philosophical Journal, 

 vol. IX. p. 366 ; Farquharson, ib. vol. vi. p. 392 ; Wrangel, 

 Phys. Beob. S. 59 ; Parry, Journal of a Second Voyage, 

 performed in 1821—1823, p. 156) saw a great Aurora con- 

 tinue through the day. Something of the same kind was 

 seen in England, 9th Sept. 1827. At mid-day, a luminous 

 arch, 20O high, and rays shooting from it, were perceived 

 after rain, in a part of the heavens that had become clear. 

 Journal of the Royal Institution of Great Britain, 1828, 

 Jan., p. 429. 



144 (p. 59.) — After my return from my American travels. 

 I described the cirro-cumulus cloud — when it appears very 

 regularly divided into rounded masses as if by the agency 

 of repulsive forces— under the name of polar streaks (bandes 

 polaires), because their perspective point of convergence is 

 mostly in the magnetic meridian in the first instance, so 

 that the parallel rows of cumuli follow the magnetic merid- 

 ian. One peculiarity of this enigmatical phenomenon is, 

 the swaying hither and thither of the point of convergence. 

 Usually the streaks are only completely developed in one 

 region of the sky, and in their motion they are seen directed 

 first from south to north, and then gradually veering round 

 from east to west. I cannot ascribe the advance of the 

 zones to any change in the quarter of the wind in the supe- 

 rior strata of the atmosphere. They arise when the air is 

 extremely calm and the heaven is particularly serene, and 

 under the tropics are far more common than in the temper- 

 ate and frigid zones. I have observed the phenomenon 

 among the Andes, when I was at the height of 14,000 feet 

 above the level of the sea, as well as in Northern Asia, in 

 the plains of Krasnojarski, southward from Buchtarminsk, 

 and in both instances so much alike, that the natural pro- 

 cess in virtue of which it takes place must be regarded as 

 one of very extensive prevalence. See the important ob- 

 servations of Kaemtz (Vorlesungen Uber Meteorologie, 1840, 

 S. 146) ; also those of later date, or Martins and Bravais' 

 M6t6orologie, 1843, p. 117. In an exhibition of south polar 

 streaks of very delicate clouds, which Arago observed by 

 day on the 23d of June, 1844, at Paris, dark rays shot up- 

 wards fromjan arch which was directed from east to west. 

 We have above (p. 59) referred to darker polar lights— to 

 rays bearing some resemblance to dusky smoke. 



145 (p. 60.)— The northern lights are called "the merry 

 dancers" by the inhabitants of the Shetland Islands. Ken- 

 dal, in Quarterly Journ. of Science, new series, vol. iv. p. 395. 



146 (p. 60.)— See the admirable work of Muncke, in the 

 new edition of Gehler's Physik. Worterbuch, Bd. vii. 1, 

 S. 113-268, particularly S. 156. 



147 (p. 60.)— Farquharson, in Edinb. Philos. Journal, vol. 

 xvi. p. 304 ; Philos. Transact, for 1629, p. 113. 



148 (p. 60.)— Kamtz, Lehrb. der Meteorologie, Bd. iii. S. 

 498. 501. 



149 (p. 61.)— Arago on the dry fog of 1783 and 1831, which 

 illuminated the night, in Annuaire for 1842 ; and on extra- 

 ordinary luminous phenomena in clouds without storms, 

 vide Annuaire for 1638, p. 279. 



160 (p. 62.)— Herodotus, iv. 28. The old prejudice (Pliny, 

 ii. 80), that Egypt never suflTers from earthquakes, is an- 

 swered by the colossal statue of Memnon, which has been 

 again restored (Letronne, La Statue vocale de Memnon, 

 1833) ; but the valley of the Nile does lie without the circle 



of concussion of Byzantium, the Archipelago, and .Syria 

 (Ideler ad Aristot. Meteor, p. 584). 



151 (p. 62.)— Saint-Martin, in the learned notes to Le- 

 beau. Hist, du Bas Empire, t. ix. p. 401. 



152 (p. 62.)— Humboldt, Asie centrale, t. ii. p. 110— 118. 

 On the difference between concussion of the surface and 

 the strata lying under it, vide Gay-Lussac, in the Annales 

 de Chimie et de Physique, t. xxii. p. 429. 



153 (p. 62.)— Tutissimum est cum vibrat crispante aedifi- 

 ciorum crepitu ; et cum intumescit assurgens alternoque 

 motu residet, innoxium et cum concurrentia tecta contrario 

 ictu arietant ; quoniarn alter motus alteri renititur. Un- 

 dantis inclinatio et fluctus more quaedam voiutatio infesta 

 est, aut cum in unam partem totus se motus impellit (Plin. 

 ii. 82). ^ 



154 (p. 62.) — Even in Italy they have begun to acknowledge 

 the independence of earthquakes of the state of the weather, 

 i. e. the appearance of the heavens immediately before the 

 concussion. F. Hoff'mann's numerical results accord in all 

 respects with the experience of the Abb6 Sciiia, of Palermo 

 (Posthum. Works, vol. ii. p. 386- .395). 1 have myself sev- 

 eral limes o!)served reddish clouds on the day of shocks, 

 and shortly before they happened ; on the 4th Nov. 1799, 

 indeed, I experienced two smart shocks at the moment of s 

 loud clap of thunder (Relat. Hist. liv. iv. chap. 10). Va- 

 salli Eandi, of Turin, observed Volta's electrometer much 

 agitated during the protracted earthquake of Pignerol, April 

 2 to May 17, 1808 (Journ. de Physique, t. Ixvii. p. 291). 

 But these signs from clouds, from altered aerial electricity, 

 and from calms, cannot be regarded as universally signifi- 

 cant, as necessarily connected with earthquakes. In Quito, 

 Peru, and Chili, as well as in Canada and Italy, many 

 earthquakes are observed along with the clearest skies, 

 with the freshest land and sea-breezes. But if no meteoro* 

 logical indicatitm present itself on the day of the shock, ot 

 shortly before this occurs, it seems impossible to overlook 

 the influence of particular seasons (the vernal and the au- 

 tumnal equinoxes), i. e. the commencement of the rainy sea- 

 son after long drought within the tropics, and the change 

 of the monsoons according to popular belief, although we 

 cannot perceive the genetical connection of meteorological 

 processes with what takes place in the interior of the earth. 

 Numerical inquiries on the distribution of earthquakes 

 throughout the course of the year, such as have been insti- 

 tuted with great industry by Von Hoff, Merian, and Fried. 

 Iloff'mann, vouch for their frequency at the epochs of the 

 equinoxes. It is very remarkable that Pliny designates an 

 earthquake a subterraneous thunder-storm, not so niuch by 

 reason of the rolling noise as because he holds tliat the 

 elastic concussive forces acting through their tension accu- 

 mulate in the interior of the earth when they are absent in 

 the atmosphere: Ventos in causa esse non dubium reor. 

 Neque enim unquam intremiscunt terrae, nisi sopito marl 

 caeloque adeo tranquillo, ut volatus avium non pendeant, 

 subtracto omni spiritu qui vehit ; nee unquam nisi post 

 ventos conditos, scilicet in venas et cavernas ejus occulto 

 afflatu. Neque aliud est in terra tremor, quam in nube 

 tonitruum ; nee hiatus aliud quam curn fulmen erumpit, 

 incluso spiritu luctanre et ad libertatein exire nitente (Plin. 

 ii.79; in Seneca, Nat. Quaest. vi. 4 — 31). In these words 

 we see the germ of all that has since been said soberly, or 

 dreamed on the causes of earthquakes. 



[Mr. Edmonds— Cornwall Journal (?)— has endeavoured 

 to connect the occurrence of earthquakes with the period 

 of the moon. He shows that a great number of the most 

 disastrous have occurred the day after the first quarter. 

 — Tr.] 



155 (p. 62.)— I have given data which show that the hour- 

 ly variation of the barometer is not affected before or after 

 earthquakes, in my Relat. Hist. t. i. p. 311 and 513. 



156 (p. 62.)— Humboldt, Rel. Hist. t. i. p. 515-517. 



157 (p. 63.)— On the Bramidos of Guanaxnato, vide my 

 Essai polit. sur Ijj Nouv. Espagne, t. i. p. 303. The sub- 

 terraneous noises without any appreciable movement of the 

 earth in the deep mines or on the surface (6420 feet above 

 the level of the sea) were not heard in the lofty table-lands 

 in the neighbourhood, l)Ut only in the hilly parts of the 

 Sierra, from the Cuesta de los Aguilares, not far from Mar- 

 sili Ufirthward, to Santa Rosa. And the waves of sound did 

 not reach to particular parts of the Sierra 6 or 7 miles 

 north-west of Guanaxualo to the other side of Chichime- 

 quillo, near the boiling spring of San Jos6 de Comangillas 

 Very severe measures were taken by the magistracy of th 

 mountain town, when the alarm at the sounds was at its 

 height. " 1 4th Jan. 1784.— The flight of a family of wealthy 

 persons shall be punished with a fine of 100 piastres ; that 

 of poor persons with two months' imprisonment. The mi- 

 litia are empowered to bring back fugitives." Not the least 

 remarkable point is the opinion which the gentry (el Ca- 

 bildo) are to form from their belter knowledge : " The 

 gentry, in their wisdom (en su Saltidura), will know when 

 there is any danger, and then they may recommend flight ; 

 for the present, processions are all that are requisite." A 

 famine was the consequence of the alarm for the truenos ; 



