262 Descripl'ion of an inclosed Grindstone 



Upper Ashop, in Hope Woodlands, NW (Combs-Tor), 



very large; (Dine-Sitch Tor): and N (Collet Hay). 

 Wensley, near VV^insler, N. 

 Willersley, in Matlock, NFl 

 Wirksworth, NW (Bole- Hill). 

 Woodhead, Cheshire, SE. 

 W^oodseats-Hall, in Barlow, i m. SW, in 2nd Coal Shale. 



All the above Slips, except five, which are mentioned, 

 and numerous olhtr smaller ones, are occasioned by the 

 Limestone Shale ; sometimes the sunk pieces contain part 

 of the 1st Grit Rock on the Shale, or large pieces of shale 

 Grit, or shale Limestone, perhaps, in their masses. 



As in the judijement of some I shall be thought, pro- 

 bablv, to have said loo nnuch already on the form and sur- 

 face of the County, I shall now close this Section by men- 

 tioniiia, that Derbyshire contains about 972 square English 

 miles, or 622,080 statute acres*. 



XXXVII r. Description of an inclosed Grindstone, intended 

 to prevent prejudicial Effects to the Persons employed i?i 

 pointing Needles. By Mr. Thomas Wood f. 



Sir, X HEREWITH submit to the inspection of the Society 

 instituted for the Encouragement of Arts, &c. a model of 

 an inclosed grindstone, intended to prevent prejudicial ef- 

 fects to the persons employed in pointing needles. 



This grindstone is inclosed in a case of wood or metal, 

 and hath a hood wherein a square of glass is inserted, de- 

 sif^ned to admit light on the articles under operation. 



The particular advantages attending a grindstone suspend- 

 ed in this maimer, with a hood and a damp cloth, are, that 

 the stream or current of air, formed by the motion of the 

 stone on its axis, is confined by the case under the hood of 



* Which is the result of a careful scaleing of my large Map. In the Ori- 

 einal Report, Mr. Thomas Brown stated the quantity at 720,6'10 acrc'i ; the 

 Parliamentary Returns of the Poor's Rates, as slated by Mr. 'Iliomas Poole, 

 make Derbyshire contain 689,'.^80 acres, which last, considering that many 

 of the Parish quantities must have be^n st:!tcd by estimation, agrees suffi- 

 ciently near with mineabove. About the year 1756, when Benjamin Mnrtin 

 published his Natural History of Engl;;i:d, this County was stated to contain 

 only 540,800 acres; but a Dictionary of .(Vrts and Sciences, now publishing 

 in London, magnifies its dimensions to 1,600 000 acres! See other particu- 

 lars of the acres in thi:- County, in ijeciions IV. and VI. of this Ciiapter. 



f From Trnnsaclious of the Society fur the Eiicourn^ement nf Arts, Manvfac- 

 hires, and Commerce, for 18 1 I. — The silver medal of the Socie'y was voted 

 to Mr. Wood for this invention, and a model of the Apparatus is preserved 

 ill the Society's Repository. 



which 



