182 REPORT— 1875. 



■wliich is limited to discussions directly arising on facts within the reach of obser- 

 vation, or on reasonings based on such facts. It is a necessary condition of the 

 progress of knowledge that the line between what properly is or is not within the 

 reach of human intelligence is ill defined, and that opinions will vary as to where it 

 should be drawn ; for it is the avowed and successful aim of science to keep this 

 line constantly shifting by pushing it forward ; many of the efforts made to do this 

 are no doubt founded in error, but all are deserving of respect that are imdertaken 

 honestly. 



The conception of evolution is essentially that of a passage to the state of 

 things which observation shows us to exist now, from some preceding state 

 of things. Applied to Geography, that is to say to the present condition of 

 the earth as a whole, it leads up to the conclusion that the existing outlines of sea 

 and land have been caused by modifications of pre-existing oceans and continents, 

 brought about by the operation of forces which are still in action, and which have 

 acted from the most remote past of which we can conceive ; that all the successive 

 forms of the surface, — the depressions occupied by the waters, and the elevations 

 constituting mountain- chains, — are due to these same forces ; that these have been 

 set up, fu-st, by the secidar loss of heat which accompanied the oi'iginal cooling of the 

 globe, and second, by the annual or daily gain and loss of heat received from 

 the sun acting on the matter of which the earth and its atmosphere are composed ; 

 that all variations of climate are dependent on differences in the condition of the 

 siu^face ; that the distribution of life on the earth, and the vast varieties of its forms, 

 are consequences of contemporaneous or antecedent changes of the forms of the surface 

 and climate ; and thus that our planet as we now find it is the result of modifi- 

 cations gradually brought about in its successive stages, by the necessary action of 

 the matter out of which it has been formed, imder the influence of the matter 

 which is external to it. 



I shall state briefly the grounds on which these conclusions are based. 



So far as concerns the inorganic fabric of the earth, that view of its past history 

 which is based on the principle of the persistence of all the forces of nature, may 

 be said to be now universally adopted. This teaches that the almost infinite variety 

 of natural phenomena arises from new combinations of old forms of matter, imder 

 the action of new combinations of old forms of force. Its recognition has, however, 

 been comparatively recent, and is in a great measure due to the teachings of that 

 eminent geologist, the late Sir Charles Lyell, whom we have lost during the past 

 year. 



When we look back by the help of geological science to the more remote past, 

 through the epochs immediately preceding our own, we find evidence of marine 

 animals — which lived, were reproduced, and died, — posssessed of organs proving 

 that they were under the influence of the heat and light of the sun ; of seas whose 

 waves rose before the winds, breaking down cliffs, and forming beaches of boidders 

 and pebbles ; of tides and ciu-rents spreading out banks of sand and mud, on which 

 are left the impress of the ripple of the water, of drops of rain, and of the trade of 

 animals ; and all these appearances are precisely similar to those we observe at the 

 present day as the result of forces which we see actually in operation. Every suc- 

 cessive stage, as we recede in the past history of the earth, teaches the same lesson. 

 The forces which are now at work, whether in degi-ading the surface by the action 

 of seas, rivers, or frosts, and in transporting its fragments into the sea, or in recon- 

 stituting the land by raising beds laid out in the depth of the ocean, are traced by 

 similar effects as having continued in action from the earliest times. 



Thus pushing back om- inquuies we at last reach the point where the apparent 

 cessation of teiTcstrial conditions such as now exist requires us to consider the 

 relation in which our planet stands to other bodies in celestial space ; and vast 

 though the gulf be that separates us from these, science has been able to bridge it. 

 By means of specti'oscopic analysis it has been established that the constituent 

 elements of the sim and other heavenly bodies are substantially the same as those 

 of the earth. The examination of the meteorites which have fallen on the eartli 

 from the interplanetary spaces shows that they also contain nothicg foreign to 

 the constituents of the earth. The inference seems legitimate, coiToborated as it is 

 by the manifest physical connexion between the sim and the planetary bodies 



