[Footnote 156:  According to the latest accounts I have been able to obtain, a temperature of 29.75 deg.  F. had already been reached some years ago; the temperature, a few feet from the surface, being 14 deg. below freezing.  The soil here only thaws to a depth of 3 feet in the hottest summer.  Sir R. Murchison wrote to Russia, in February last, for further information regarding this well.

Since I wrote this, Sir Roderick Murchison has applied to the Secretary of the Imperial Academy of St. Petersburg for further information respecting the investigations at Jakutsk.  The Secretary gives a reference to Middendorff’s Sibirische Reise, Bd. iv.  Th. i., 3te Lieferung, Klima, 1861.  I have only been able to find the edition of 1848-51; but in that edition, under the heading Meteorologische Beobachtungen, elaborate tables of the meteorological condition of Jakutsk are given (i. 28-49).  Also, under the heading Geothermische Beobachtungen, very careful information respecting the frozen earth will be found (i. 157, &c., and 178, &c.).  The point at which a temperature of 32 deg. will be attained, is reckoned variously at from 600 to 1,000 feet below the surface.]

[Footnote 157:  Reise im Russischen Reich_, i. 359; St. Petersburg, 1772.]

[Footnote 158:  xxxviii. 231 (an. 1791), in an article called Notice mineral, de la Daourie]

[Footnote 159:  L.c., p. 236.]

[Footnote 160:  Beobachtungen, &c., 194.]

[Footnote 161:  Mundus Subterraneus, i. 220 (i. 239, in the edition of 1678).]

[Footnote 162:  ’Vidi ego in Monte Sorano cryptam veluti glacie incrustatam, ingentibus in fornice hinc inde stiriis dependentibus, e quibus vicini mentis accolae pocula aestivo tempore conficiunt, aquae vinoque quae iis infunduntur refrigerandis aptissima, extremo rigore in summas bibentium delicias commutato.’]

[Footnote 163:  Both here and at Schemnitz, Kircher made particular enquiries on a subject of which scientific men have altogether lost sight.  At Schemnitz he asked the superintendent, an comparcant Daemunculi vel pygmaei in fodinis?—­respondit affirmative, et narrat plura exempla; and at Herrengrund, utrum appareant Daemunculi seu pygmaei?—­respondit tales visos fuisse, et auditos pluries. (Edition of 1678, ii. 203, 205.)]

[Footnote 164:  Reich, 199.]

[Footnote 165:  i. 108 (Lyon, 1794).]

[Footnote 166:  Ueber die unterirdischen Gasarten, 101.]

[Footnote 167:  xvii. 386.]

[Footnote 168:  Mem. sur les Basaltes de la Saxe, p. 147.]

[Footnote 169:  Mineralog.  Reisen, ii. 123.]

[Footnote 170:  Reich, 200, 201; Bischof, Physical Researches on the Internal Heat of the Globe, 46, 47.]

[Footnote 171:  Peters, Geologische und mineralogische Studien aus dem sudoestlichen Ungarn, in the Sitzungsberichte der kais.  Ak. in Wien, B. xliii., 1te Abth., S. 435.  See also pages 394 and 418 of the same volume (year 1861).]