OF EAKTH. 



19 



you shall collect from the subsidence (to appearance) of the most crystal 

 waters, precipitated by deliquated oil of tartar, or the like ; and the more 

 they be subdued and broken, the harder they will prove, if (cleared of 

 their nitrous parts) they pass the potter's fire, however they seemed 

 before to be of different constitution. This is evident in vessels made of 

 tobacco-pipe clay, or whatever the material be, which has of late been 

 so successfully employed by Dr. Hook, a worthy member of this Society, 

 for the finding out a composition (if I may so call it) nothing inferior to 

 the hardest porcelain, and almost as beautiful. And now upon contem- 

 plation of that almost universal ingredient, sand, through all our trials, 

 I cannot but incline to the sentiment of that excellent philosopher, as - 

 well as physician, the learned Dr. Lister, that sand might be the first 

 mantle and universal covering of the newly-created earth. See his dis- 

 course upon a map, discovering sands and clay, reduced to tables, pre- 

 sented to the Royal Society '. 



But to return to our superficial earth, which we call the mould. I 

 affirm it to grow and increase yearly in depth from the causes aforesaid ; 

 and, in some places, to that proportion as to have raised no inconsiderable 

 hills and eminences by the accidental fall and rotting of woods and trees, \ 

 such as Birch, Beech, &c. which are not of a constitution to remain long- 

 in the ground (as Fir, Oak, Elm, and some other timber will do, and 

 grow the harder) without corruption, and relenting into mould as soft 

 and tender as what they first were sown or planted in ; and of this I am 

 able to give undeniable instances. I insist not here on the perpetual suc- 

 cessions and generations of flints and other stones, in the same places 



* Dr. Lister was of opinion, that, by examining the earth from the surface downwards, 

 as often as an opportunity offered, a pretty just theory might be formed of its contents in 

 general : for it appeared from his own observations, that upper natural soils infallibly pro- 

 duce the same internal minerals and materials. He has tlirown out a hint to every na- 

 turalist for extending this useful knowledge, by advising that a soil or mineral map should 

 be made, properly distinguished into countries, and enriched with observations for general 

 use, arising from remarks on the bounds and produce of every particular soil. — The doctor 

 likewise thought that sand was once the exterior and general cover of the surface of the 

 whole earth, and that clay was another coat in the more depressed and hollow parts. The 

 following are his tables of sands and clays which he drew up in l673, from observations 

 made in the northern parts of England, and is the matter here referred to by Mr. Evelyn. 



S H 2 



