296 Analyses of Books. [Apiut, 



boidal, and tabular, of all which we are at no loss for examples 

 in this county." 



II. and III. On the Temperature of Mines. By Robert W. 

 Fox, Esq. MGSC. 



IV. On the Stratified Deposits of Tin-stone, called Tin-floors, 

 and m the Diffusion of Tin-stone through the Mass of some pri- 

 mitive Rocks. By J. Hawkins, Esq. FRS. &c. Hon. Mem. GSC. 



In Cornwall, Mr. Hawkins observes, the veins of tin are so 

 rich and so numerous, that, with the exception of the alluvial 

 beds of that metal, in the stream-works, every other mode of its 

 deposition in the earth seems to have been disregarded. He 

 then expresses his opinion that the same interest of capital 

 which is obtained by working the tin-lodes, or even a greater, 

 " might be obtained, with infinitely less fluctuation in its amount, 

 from situations where nature has scattered her favours with a 

 more sparing hand, but in a more equal manner : " alluding " to 

 those mineral deposits, which our miners call tin-floors, and more 

 particularly to those important objects of mining industry, which 

 the Saxons call stock-works, should they be found to exist here." 



These remarks are succeeded by some information on both 

 these subjects, partly extracted from the author's own journals, 

 and partly from the printed reports of very accurate observers. 

 Tin-floors "are said to occur at Bal-an-uiin, in the parish of 

 Lelant, and at Huel-grouan in the parish of Breage ; and, if I 

 am rightly informed," continues the author, " Curclaze mine, 

 near St. Austle, belongs to this class, and merits a very parti- 

 cular examination." The tin-floors on the sea-cliffs of the 

 parish of St. Just are next described ; but we shall extract a 

 more particular account of these from a subsequent paper, by 

 Mr. Came. Such beds are not unfrequent, it is stated, in the 

 highest ridge of the mountains which constitute the boundary 

 line between Saxony and Bohemia. Those at Zinnwald are on 

 one of the highest points on the Bohemian side; "the strata here 

 consist of a fine grained, half decomposed granite, which alter- 

 nates with the tin-floors. These again consist of quartz, mica, 

 and gneiss," in the two latter of which the tin is found inter- 

 spersed together with fluor spar and wolfram. " Similar floors, 

 composed of magnetical ironstone, tinstone, and pyrites, occur 

 in other parts of the same range of mountains :" the most con- 

 siderable of these is situated at Breitenbrunn. 



What are called tin-floors at Trewidden Bal mine, in the parish 

 of Madron, in Cornwall, are, correctly speaking, " small, very 

 short fissures or veins, which run partially through the elvan, 

 varying in breadth from half an inch to eight or nine inches, and 

 so irregular and interrupted as to render it difficult to ascertain 

 either their direction or their underlie. These small capricious 

 veins appear frequently to diverge from a central body, and then 

 bear some resemblance in form to the spreading roots of a tree/' 

 It is afterwards stated, from another part of the author's journal, 



