6o APHORISMS AND REFLECTIONS 



CLXXXIX 



A great chapter of the history of the world is 

 written in the chalk. Fev'f passages in the history 

 of man can be supported by such an overwhelm- 

 ing mass of direct and indirect evidence as that 

 which testifies to the truth of the fragment of the 

 history of the globe, which I hope to enable you 

 to read, with your own eyes, to-night. Let me 

 add, that few chapters of human history have a 

 more profound significance for ourselves. I weigh 

 my words well when I assert, that the man who 

 should know the true history of the bit of chalk 

 which every carpenter carries about in his 

 breeches-pocket, though ignorant of all other 

 history, is likely, if he will think his knowledge 

 out to its ultimate results, to have a truer, and 

 therefore a better, conception of this wonderful 

 universe, and of man's relation to it, than the 

 most learned student who is deep-read in the 

 records of humanity and ignorant of those of 

 Nature. 



cxc 



The examination of a transparent slice gives a 

 good notion of the manner in which the components 

 of the chalk are arranged, and of their relative pro- 

 portions. But, by rubbing up some chalk with a 

 brush in water and then pouring off the milky fluid, 

 so as to obtain sediments of different degrees of fine- 

 ness, the granules and the minute rounded bodies 

 may be pretty well separated from one another, and 

 submitted to microscopic examination, either as 

 opaque or as transparent objects. By combining the 

 views obtained in these various methods, each of 

 the rounded bodies may be proved to be a beautifully- 

 constructed calcareous fabric, made up of a number 

 of chambers, communicating freely with one another. 

 The chambered bodies are of various forms. One of 

 the commonest is something like a badly-grown 



