30 Dr. Berger ow the Isle of Man. 



a minute investigation both of the rocks and simple minerals had 

 never been yet instituted, and the arrangement and examination o 

 the high land, the most conspicuous and extensive part of the isle, 

 still remained a field quite unexplored. 



The grotesque and unfaithful attempt of Fannin to lay down 

 the mountains in his map of the island published in 1789, can hardly 

 be considered as an improvement upon the much earlier and rough 

 sketches of Collins, Durham and Speed. 



From the materials and documents which I collected when in the 

 Isle of Man, I have since my return from Ireland constructed a map 

 chiefly expressive of the features and appearances of the mountain- 

 ous tract, which I now present to the Society ; acknowledging at 

 the same time the able and kind assistance afforded me by Mr. 

 Webster, draughtsman to the Society.* 



The height of Snei-feldt was a long time ago determined by 

 means of the barometer, by Bishop Wilson, f and it has been since 



* This map however is neither complete nor as perfect as I wish I had been able io 

 execute it. Mr, Wm. Gencste (a gentleman of Douglass, io whom I am much indebted) 

 Las had the complaisance to undertake last Summer at my request, a trigonometrical 

 survey of the Isle of Man, conjointly with Mr. James Kewley, a person who has for- 

 merly practised as a Surveyor. But I fear the result of their labours, which Mr. W. G. 

 intended with a great liberality to put at my disposal, will not be ready io be published in 

 this volume of the Transactions of the Geological Societj'. 



t The height of Snajield (says the Bishop) as taken by an exact barometer, is about 

 five hundred and eighty yards, the mercury subsiding two inches and one tenth. Vol. I. 

 p. 449. 



This is very probably the first application that was made of the barometer in Great 

 Britain to determine the elevation of a mountain. 



The original experiment pointed out by Pascal, was performed by Perier (his brother- 

 in-law) on the " Puy de Dome," 19th Sept. 1648. Bishop Wilson came over to the Isle 

 of Man in April 1698, where during his long residence, he made th« experiment that led 

 him to the elevation of Snei-feldt. 



