In PERTHSHIRE. 245 



reclion from their centre. They are commonly obferved at 

 Lawers on the eaft ; throughout the whole of Glen-Leadnach,at 

 Dunira, Dalchonzie and Aberuchill, on the north and weft ; and 

 do not reach fo far as the manfe, which is about three quarters 

 of a mile on the fouth of Comrie *. 



I am, with great regard, 



Dear Sir, 



Your's mod fincerely, 



Ralph Taylor. 



POSTSCRIPT. 



Duddingjione Houfe, Jan. 24. 1793. 



There is no reafon to believe, that thefe phenomena are yet 

 come to an end. After temporary intermiiTions, fometimes of 

 feveral months, they have returned, ever fince their firft ap- 

 pearance in 1789, without any apparent difference in their 



extent 



* The tract within which the concuffions defcribed in this letter appear to have been 

 confined, is a fpace of a rectangular form, which extends from eaft to weft along the north 

 fide of the Earn about 22 miles in length, by a little more than five in breadth ; reckon- 

 ing the utmoft length from about Monzie to the head of Loch Tay, and the breadth 

 from" a little fouth of the Earn nerthward to the ridge which feparates the branches of 

 that river from thofe of the Almond. The whole of this tract is mountainous, except 

 toward the eaftern- extremity, where it joins the low country, and on the banks of the 

 river Earn on the fouth. It is interfered by narrow glens or valleys, the moft confider- 

 able of which is Glen-Leadnach, where the centre of the concuffions feems to be placed. 

 The mineralogy of this part of the country has not hitherto been accurately examined j 

 but it is known in general, that the ftone is the primary fchiftus, and in fome places 

 granite ; that no mineral veins, nor any hot fprings, have been found in it, and that no 

 volcanic appearances have been obferved. In the valleys, among the mountains, iron 

 ore, of the kind that is called bog ore, is laid to abound. Dr Hutton has remarked, that 

 th<: line which terminates this tract on the S. E. feems to be nearly the fame with that 

 where the primary ftrata fink under the furface, and are covered by the fecondary, or 

 horizontal ftrata. J. P. 



