APPENDIX. 435 



sophic systems, to crop and prune them to predetermined shapes. Whith- 

 er the known points us, let us follow ; and if we can not discern things 

 clearly, let us be content to see them " through a glass darkly. " It would 

 be stupidity to ignore the existence of a solar orb even in total eclipse. 



This revulsion in the popular view has to some extent been produced by 

 the weight of well-known names recorded against the doctrine of primor- 

 dial fusion and continued central fluidity. Sir David Brewster denounces 

 "the nebulous theory" as "utter nonsense;" and Mr. Evan Hopkins has 

 publicly denied the accepted doctrine of a slow increase of temperature in 

 penetrating toward the earth's centre. It is certain, however, that the 

 facts upon which his denial rests have been generated by abnormal and 

 perturbating influences. Mr. W. Hopkins several years since contended 

 that the solidification of the earth must have begun at the centre, simul- 

 taneously with the formation of the superficial crust. Sir Wm. Thompson 

 maintains that the rigidity of the earth is required by the phenomena of 

 precession and nutation. Against these conclusions, however, Delauny 

 very recently opposes the results of experiments which show that a body 

 of water inclosed in a rotating glass globe promptly partakes of the rota- 

 tion of the globe, and becomes physically a part of it. The author re- 

 mains decidedly of the opinion that the balance of evidence sustains the 

 doctrine of central fluidity. The reader who desires to examine farther 

 the objections urged against this doctrine may consult Hopkins (Wm.), 

 in Phil. Trans, of the Royal Society, 1836, p. 382 ; also 1839-40-42 ; also 

 Quar. Jour. Geolog. Soc, Lond., vol. viii., p. 56 ; Thompson (W.), on the 

 Rigidity of the Earth, in Proceedings Roy. Soc, vol. xii., p. 103; Tyn- 

 dall, in Fortnightly Review. On the subject of mountain-formation, see 

 Hall (James), Paleontology of New York, vol. iv., Introduction; Dana 

 (J. D.), Address before the Amer. Assoc, for the Advancement of Science, 

 Providence, 1857. 



Note II., page 71. 

 As the recent discovery of traces of animal life two whole systems low- 

 er in the series of strata than had heretofore been known is an event of 

 extraordinary importance in the progress of our knowledge of the world's 

 preadamic history — insomuch that Sir Charles Lyell characterizes it as the 

 greatest geological discovery of his time — I introduce here a somewhat 

 complete series of references to the papers which have been published on 

 the subject : 



1858, May. Hunt (Dr. T. S.), Remarks on the presence of iron ores and 

 graphite in Laurentian strata as affording evidence of the "exist- 

 ence of organic life even during the Laurentian or Azoic period. " 

 Amer. Jour. Sci. and Arts [2], xxv., 436. 

 1858, Oct. Logan (Sir W. E.) received the first specimens of suspected 



