15
you shall collect from the subsidence (to appearance) of the most crystalwaters, precipitated by deliquated oil of tartar, or the like; and the morethey be subdued and broken, the harder they will prove, if (cleared oftheir nitrous parts) they pafs the potter’s fire, however they seemed be-fore to be of different constitution. This is evident in vefsels made of to-bacco-pipe clay, or whatever the material be, which has of late been sosuccefsfully employed by Dr. Hook, a worthy Member of this Society,for the finding out a composition (if I may so call it) nothing inferior tothe 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 wellas physician, the learned Dr. Lister, that sand might be the first mantleand universal covering of the newly-created earth. See his discourfe upona map, discovering sands and clap, reduced to tables, presented to the RoyalSociety ‘.
But to return to our superficial earth, which we call the Mould . I af-firm it to grow and increase yearly in depth from the causes aforesaid ;and, in some places, to that proportion as to have raised no inconsiderablehills 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 longin the ground (as Fir, Oak, Elm, and some other timber will do, andgrow the harder) without corruption, and relenting into mould as softand tender as what they first were sown or planted in; and of this I amable to give undeniable instances. I insist not here on the perpetual suc-cefsions 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 ingeneral: for it appeared from his own observations, that upper natural soils infallibly pro-duce the same internal minerals and materials. He has thrown out an hint to every na-turalist for extending this useful knowledge, by advising that a soil or mineral map shouldbe made, properly distinguished into countries, and enriched with observations for generaluse, arising from remarks on the bounds and produce of every particular soil.—The Doctorlikewise thought that sand was once the exterior and general cover of the surface of the■wholp earth, and that clay was another coat in the more depressed and hollow parts. Thefollowing are his Tables of Sands and Clays which he drew up in 1673, from observationsmade in the northern parts of England, and is the matter here referred to by Mr. Evelvn.
3 H 2