lii REPORT — 1853. 



than 30° Fahr,, about one-fifth of the whole temperature at which it melts 

 under the pressure of the atmosphere. We have not yet ascertained the 

 degree in which the conductive power of any substance may be increased 

 when solidified under great pressure. This point we hope to investigate with 

 due care, and also to determine the effects on substances tlius solidified, with 

 respect to their density, strength, crystalline forms, and general molecular 

 structure. We thus hope to obtain results of general interest and value, as 

 well as those which may bear more directly on the questions which first sug- 

 gested the experiments. 



Among researches for determining the nature of the earth's crust at depths 

 greater than those to which we can penetrate, I must not omit mention of 

 Mr. Mallet's very elaborate Report on Eartiiquakes, contained in the two 

 last volumes of the Reports of the Association. His Earthquake catalogue 

 is preceded by an account of some very interesting and carefully conducted 

 experiments on tiie transmission of vibrations through solid media. These 

 results will be found of great value whenever the subject of earthquakes 

 shall receive that careful attention which it so well deserves. Insulated 

 observations, and those casual notices which are now frequently given of 

 earthquake plisenomena, are utterly useless for scientific ])urposes. There 

 are no observations which more require to be regulated by system and com- 

 bination than those of the phajnomena in question ; and I sliould rejoice to 

 see the influence of the Association exerted for this purpose, when some 

 efficient mode of proceeding shall have been devised. 



Some of the most interesting of recent discoveries in Organic Remains are 

 those wliich prove tiie existence of Reptilian life during the deposition of 

 some of our oldest fossiliferous strata. An almost perfect skeleton of a 

 reptile belonging to the Batrachians or Lacertians, was lately found in the 

 old red sandstone of Morayshire. The remains of a reptile were also disco- 

 vered last year, by Sir Charles Lyell and Mr. Dawson, in tiie coal-measures 

 of Nova Scotia ; and a Batrachoid fossil has also been recognized in British 

 coal shale. But the most curious evidence of tlie early existence of animals 

 above the lower orders of organization on the face of our globe, is that 

 afforded by the footprints discovered a siiort time ago in Canada, by Mr. 

 Logan, on large slabs of some of the oldest fossiliferous rocks — those of the 

 Silurian epoch. It was inferred from the more imperfect specimens first 

 brought over, that these footmarks were tliose of some reptile, but more per- 

 fect examples, afterwards supplied by Mr. Logan, satisfied Prof. Owen that 

 they were the impressions of some animal belonging to the Articulata, pro- 

 bably a crustacean. Thus the existence of animals of the reptile type of 

 organization during the Carboniferous and Devonian periods is clearly esta- 

 blislied, but no evidence has yet been obtained of the existence of those 

 animals during tiie Silurian period. After the discoveries I have mentioned, 

 however, few geologists will perhaps be surprised should we hereafter find 

 that higher forms of animal life were introduced upon the earth during this 

 early period than have yet been detected in its sedimentary beds. 



Many of you will be aware that there are two theories in geology which 

 may be styled the theories of progression and non-progression respectively. 

 The former asserts that the matter which constitutes the earth has passed 

 through continuous and progressive changes from the earliest state in which 

 it existed to its actual condition at the present time. The earliest state here 

 contemplated may have been a fluid, or even a gaseous state, due to the 

 enormous primitive heat of the mass, and it is to the gradual loss of that 

 iieat that the progressive change recognized by this theory is chiefly attri- 



