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XCI. On i lie Sliftla of Norlliiiwl^rlavd and Durham. By 

 Mr. Westgarth Forsthk. 



To Mr. Tilloch. 



Sir, — I LATELY by accident (not being a constant readey) 

 met with vour very' excellent Magazine, vol. xlv. art. 17, in 

 \vhich I have the gratification io find some encomiums made 

 upon my Treatise on a Section of the Strata, commencing near 

 Mewcastle-npon-Tyiie, &c. by Robert Bakewell, esq., for which 

 I beg leave to return my grateful acknowledgements. 



I have also taken notice of some queries, by a correspondent, 

 with the signature of " A Constant Reader," (art. 19, vol. xlv.) 

 respecting the occurrence of the grindstone-sill. In reply ; he 

 will find' the stratum, which is quarried for grindstones on 

 Gateshead-fell, at No. 10 on my section, and denominated by 

 the colliery sinkers, brown sandstone or post; the other, he will 

 find bv the provincial name of grindstone-sill, not from its being 

 quarried for grindstones, it bei?)g a coarser stratum. It probal)ly 

 derived its name from its resemblance to the above ; but it is 

 a distinct stratum, and far below the Newcastle one; and is 

 nearly the uppermost bed, on Cross-fell, Kilhope-head, Ramgill- 

 liead, Shorngate-cross, &c. 



I likewise observe, that the same correspondent is desirous 

 to know, where the iron-stone balls are lodged. Now, by re- 

 ference to my section, he will find a plate-bed where they fre- 

 quently occur, immediately above the iimhler beds of the great 

 limestone, marked 32G on the sectional scale, and commonly 

 .called by the miners cat-heads; which may very probably have 

 «' bivalve shells" inclosed, although I do not perfectly recollect 

 observing them. 



Nat. John \\'inch, esq. states, that my section has been fur- 

 bished from a similar engraving pul)lished at Carlisle (and signed 

 IFm. Millot miner, which mw^t be Miller) in the year ISOO, 

 and likewise from a section of the coal-strata suidv through at 

 Bvker St. Anthony ; together with that of Siieriff-hill colliery, 

 printed in Hutchinson's History of Durham. I 'naist vindicate 

 myself by stating to Mr. Winch, that indeed I did see Miller's 

 section previous to mv publication ; but so far from maJiing any 

 use of it, I did not copy a single stratum from it, as I found on 

 examination that it was very incorrect ; and, I believe, has been 

 taken in a great measure merely by computation. However, I 

 do not wish to claim the priority of either Miller's, or any other 

 section of the coal-measures : but this I must state, that my 

 section wa^entirely made from my own observations, and ad- 

 measurements, at several mining fields, and bassets ot tlie strata. 



Vol. 49. No. 230. June 1817.' C c oxccpting 



