92 SCIENCE IN SHORT CHAPTERS. 



varieties of bituminous coal. The fact that the products of 

 distillation of cannel and these shales form different series of 

 hydrocarbons from those of common coal, and that they 

 are nearly identical with those obtained by the distillation 

 of peat, is suggestive of origin in peat-bogs, or something 

 analogous to them. 



To the above I may add the concluding sentences of the 

 chapter on Coal in Lyell's "Elements of Geology." Speak- 

 ing of fossils in the Coal Measures, he says: "The rarity of 

 air-breathers is a very remarkable fact when we reflect that 

 our opportunities of examining strata in close connection 

 with ancient land exceed in this case all that we enjoy in 

 regard to any other formations, whether primary, secondary, 

 or tertiary. We have ransacked hundreds of soils replete 

 with the fossil roots of trees, have dug out hundreds of 

 erect trunks and stumps which stood in the position in 

 which they grew, have broken up myriads of cubic feet of 

 fuel still retaining its vegetable structure, and, after all, we 

 continue almost as much in the dark respecting the inver- 

 tebrate air-breathers of this epoch, as if the coal had been 

 thrown down in mid-ocean. The early date of the carbo- 

 niferous strata cannot explain the enigma, because we know 

 that while the land supported a luxuriant vegetation, the 

 contemporaneous seas swarmed with life with Articulata, 

 Mollusca, Kadiata, and Fishes. We must, therefore, collect 

 more facts if we expect to solve a problem which, in the 

 present state of science, cannot but excite our wonder; and 

 we must remember how much the conditions of this problem 

 have varied within the last twenty years. We must be con- 

 tent to impute the scantiness of our data and our present 

 perplexity partly to our want of diligence as collectors, and 

 partly to our want of skill as interpreters. We must also 

 confess that our ignorance is great of the laws which govern 

 the fossilization of land animals, whether of low or high 

 degree." 



The explanation of the origin of coal which I have given 

 in the foregoing meets all these difficulties. It shows how 

 vast accumulations of vegetable matter may have been 

 formed "in close connection with the ancient land," and 

 yet " as if the coal had been thrown down in mid-ocean" as 



