46 Notices respecting New Books. 



to the thickness of seven feet. The next in succession is 

 the formation of red clay, which is coinmonlv the greatest 

 in thickness of the formations. The last and uppermost 

 is the alluvial earth, which does not exceed the thickness 

 of two feet. In ihe three other pits, the diflereuce consists 

 in the relative thickness of the different strata. In the one 

 which is most advanced in a northern direction, the shells 

 are wanting ; hut teeth, similar to the others, are discovered. 



I may likewise mention that a vertical section, made 

 within the extent of a mile from this northernmost pit, af- 

 fords a quite different appearance of the stratification, as 

 immediately under a tliin covering of alluvial earth is chalk, 

 which presents a sinsmlar appearance, the layers of chalk 

 and of flints bein^; alternate through the whole depth, and 

 observing great jegularity of distance. The Thames divides 

 these two pits. 



Many parts in this island afford opportunities of de- 

 scribing differences in stratification; and when many such 

 surveys are made in parts of the globe separated from each 

 other, and these appearances accurately conipared, there is 

 no doubt but that a true theory of the mineral kingdom 

 will be the result. 



I am, sir, 



Your obedient humble servant, 



Reading, I;in. 21, 1813. D. PlENDKKLEATH, M. D. 



X. Notices respecting New Books. 



Interesting Discoveries and Researches on the Foot of the 

 liorsc. By Buacy Clark, F.L.S. &c. In two Parts. 

 Quarto. 



XAMONG other discoveries contained in this work are: — 

 The infl(.xion of the hoof at the heels, towards its centre, 

 forming an elastic how, important in diminishing the re- 

 sistance to the weight and efforts of the animal : — A re- 

 inarkable land discovered, passing from the sides of the 

 frog round the upper part of the hoof, sers'iuQ to comiect 

 it strongly with the skin, and to close the hne or joint 

 where they meet. 



The real cause of the running thrush is explained on 

 principles bel'ore unknown. 



A most in)portant defect detected, in the principle itself, 

 of modern shoeing, more injurious than the abuses com- 

 plained of, particularly to growing feet, and the elastic feet 

 of blood horses, demonstrated hy a striking and very de- 

 cisive 



