Heply to Mr. Parey*s Geological Olservat'ions. 45 



iron. I am not acquainted with any varieties of plumbago 

 which contain so small a quantity of iron, or which ex- 

 hibit such refractory properties. Those examined by 

 Scheele, Pelletier, and other able chemists, furnished more 

 iron, and differ in other respects from the subject of this 

 paper. 



X. Mr. Bakewell in Reply to Mr. Farey's Geological 

 Ohservatio7is. 



To Mr. Tilloch. 



Sir, In the last number of The Philosophical Magazine 

 voii have inserted some strictures of Mr. J. Farey on what 

 he is pleased to call an erroneous statement in my Lectures, 

 respecting a map of England, which I asserted to be, as far 

 as I knew, the first attempt to present in a distinct view " ql 

 geological outline of the arrangement of the most im- 

 portant mineral substances in South Britain." I believe 

 this was what I stated in my lectures, and notwithstanding 

 Mr. Farey's two pages on the subject I repeat the assertion 

 again. 



The week previous to the publication of Mr. Farey's 

 letter, Mr. Greenough favoured me with the inspection of 

 bis map, which I had not before seen, or even heard of. 

 With respect to what Mr. Farey or Mr. Smith may have 

 done towards producing a Geological Map of England 

 I am still unacquainted; nor am I very desirous to learn, 

 if the imaginary ^'^ zigzag fault" aud "great Derbyshire 

 fault," in the former gentleman's Survey of Derbyshire, be 

 specimens of what we mav -expect irom his geological la- 

 bours. Mr. Farey has as^serted that the metalliferous lime- 

 stone in Derbyshire is the very lowest stratum of rock ia 

 England ; on the contrary, I believe that the same lime- 

 stone, v.'hich disappears in the north-wcsi side of Derby- 

 shire, rises again in the district of Craven in Yorkshire, 

 and rests upon slate. As 1 have visited this district se- 

 veral times, and Mr. Farey, from his own acknowledgement 

 to me, has never seen it ; I presume that my evidence on 

 the subject may be entitled to as much u eight as the 

 doubts of Mr. Farcv, who has nothing to advance in their 

 support, but the existence of his imaginary great fault, for 

 which I conceive there is no proof whatever. The lime- 

 stone of Craven is as similar to that of Derbyshire, as the 

 different beds in th-it county are to each other; it contains 

 the ijamc metallic oreSj and rises Irom under a coarse mill- 

 stone 



