270 Mr. Tarty on the Pontefract Sandstone Rock. [April, 



The result of very attentive observations on the rain guage 

 throughout this year tends to confirm the conjectures offered in 

 the number of the Annals of Philosophy for July last, p. 18. 



The excess of rain received by the guage on the ground level 

 is, as before, very great at particular times, and, on the whole, 

 nearly corresponding with that of the last year, viz. 



1821 was as 1 to 1-6127 , Q i 

 100 o i i i Mi" c or as 2 to <3 nearly. 



1822 was as 1 to vo2o) J 



Among the daily differences, we found as much as 1 '5 excess ; 

 and, on the other hand, in quantities very nearly equally. The 

 least monthly excess was that of June, being -172 only, and the 

 greatest monthly excess that of December, which rose to 1-175. 

 In every instance, the excess of the lower above the upper guage 

 has been proportioned to the more or less velocity of the wind ; 

 and nothing has occurred to weaken, but much to corroborate, 

 the idea, that it is principally, if not altogether, occasioned by 

 the whirl or eddy produced by the recoil of the current of air 

 from the sides of the building. This is a question of fact, which 

 we continue to hope some of your meteorological correspondents, 

 better provided with anemometers, will try by the test of actual 

 experiments. 



Penzance, Fel. 14, 1823. 



Article VII. 



On the unconformable Position of the Pontefract Rock of Sand- 

 stone, with respect to the subjacent Coal-measures, as shown in 

 the neiv Geological Map of Yorkshire ; and regarding some 

 Errors therein, as to Parts of the Ranges of certain Rocks in 

 the Coal Series. By Mr. John Farey. 



(To the Editor of the Annals of Philosophy.) 



SIR, Hoaland-strcct, Feb. 19, 1823. 



I am one of those who have felt a strong interest in the 

 perusal of several long and very important geological papers, 

 chiefly from the pens of Messrs. Weaver, Conybeare, Buckland, 

 Phillips, Sedgwick, and Winch, which have appeared in your 

 last four volumes ; and observing that Mr. Conybeare, in p. 137 

 of your last number, considers the continental Rock, which has 

 of late been much the subject of discussion, under the name of 

 rothetiegende, to be probably the same with the English rock, 

 which my friend Mr. Smith has named the " Pontefract Rock," 

 and lately depicted its course in his four-sheet Geological Map 

 of Yorkshire, sold by Cary : I beg permission to state in your 

 Annals, that I fully concur with Mr. Conybeare in opinion, that 



