464 Conversations o?t Geology. 



Now, as a contrast to this, let us see how the subject is 

 managed in the conversational style, by the author under re- 

 view. We quote from the opening of the first conversation, 

 premising that the speakers are Mrs. R. and her two children, 

 Edward and Christina, each of whom is characterised by 

 peculiarities of sentiment and style of thinking. 



" Edward. — Sea-shells, did you say, mother, in the heart of soh'd rocks, 

 and far inland ? There must surely be some mistake in this ; at least it 

 appears to me to be incredible. 



*^ Mrs. R. — Incredible as you suppose it to be, my dear boy, you may 

 see it with your own eyes in the marble of this chimney-piece, which yoii 

 may perceive is throughout studded with shells, as if they were fresh from 

 the sea. They even retain, as you perceive, their original nacre^ as the 

 French call the peculiar lustre of mother-of-pearl. 



" Christina. — Ah, so they do ; but, I dare say, it is only a good imitation 

 of shells made on the marble. There is a very pretty one on the lid of my 

 work-box, which is certainly artificial ; and those in the marble niHy have 

 been done in the same way. 



" Mrs. R. — But, my dear, there is no nacre on the shell on your work- 

 box ; and it is evident, indeed, that it is wholly made of pieces o^ stained 

 wood, ingeniously put together : but the shells in the marble are real 

 shells, as you may see, differing in nothing from those we find on the sea- 

 shore. 



" Edward. — Then how could they come into the marble ? It must 

 have been soft, like paste, or have been precipitated or deposited, as we say 

 in chemistry, over the shells ; for they are distributed, as I perceive, through 

 its substance. 



'* Mrs. R. — Yes ; and if you were to break the marble into a thousand 

 fragments, you would find a shell in almost every one of them. 



" Christina. — Is there any history of these curious shells, mother ? I 

 should like above all things to read it. I suppose it must be something 

 like the stories I have seen of living toads found in the heart of growing 

 trees. 



" Mrs, R. — The history of the shells, my dear, and many other things 

 no less wonderful, is given in the science called Geology, which treats of 

 the first appearance of rocks, mountains, vallies, lakes, and rivers, and the 

 changes they have undergone from the creation and the deluge till the 

 present time." (p. 3.) 



As a considerable portion of the volume is devoted to the 

 two rival theories of the earth, proposed by Hutton and by 

 Werner, whose several disciples have been named Vulcanists 

 and Neptunists, because the former advocates the agency of 

 fire, and the latter the agency of water, in the formation of 

 the crust of the earth, we shall give a short sketch of the 

 leading doctrines of both systems, nearly in the words of our 

 author : — 



* For the purpose of making a globe like the earth, with seas, continents, 

 and islands, diversified with hills and vallies, and productive of food for 

 various animals, Dr. Hutton considered it as indispensable that other globes 

 should have previously existed, from which materials for the structure might 

 be derived. These supposititious worlds being acted on by the moist atmo- 

 sphere, by rains, and by the frosts and thaws of winter and spring, would, in 



