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In the third table is written the temperature of the foil, as 

 obferved in confiderable towns ; from whence it may be in- 

 ferred, that there is an artificial encreafe of heat ufually com- 

 municated to the fuiface of the earth in fuch places, varying 

 confiderably from the mean temperature of the contiguous 

 country. This is to be efteemed the refult of the warmth 

 communicated diredly from the quantity of fuel burnt in fuch 

 towns, and from the heated air and fmoke which, more or lefs. 



if great reafon to believe that the Bog of Allen, wherein is placed the fummit level 

 of the Grand Canal, is in reality elevated above a very large portion of the furface of 

 Ireland ; which may be inferred from the following circumftances : 



From the Bog of Allen the River Barrow derives the greater part of its waters ; and 

 at MonaftercA'an, (from whence it has yet a courfe of fixty-eight Irifh miles to traverfe 

 before it reaches the fouthern fea on the coaft of Waterford ;) its depreflion is eighty 

 feet below the fummit level of the Grand Canal. See Bronxinriggs fiirvey. 



From the fame fource rlfes the River Boyne, which, after a north-eaft courfe of 

 forty miles, difcharges itfelf into St. George's Channel, on the caftern coaft of the 

 kingdom (fee map of IrelmidJ ; and the elevation of the Bog of Allen is proved to be 

 two hundred and feventy feet above the eaftern coaft at Dublin. See preceding note. 



Wefterly, the defcent is every vVhere toward the Shannon, (fee furveys before par- 

 liament) even to the fource of its waters, (compare Coivens fn-vey of the Shannon 

 tvith Bronvtirigr^ s fiirvcy of the Canal j fo that this fpacious river, which, rifing from 

 the borders of the northern province of Ulfter, waihes the (liores of the three re- 

 maining provinces of Ireland through a courfe of one hundred and eighteen miles, 

 (fee Coiuen'sfiirvey) is every where confiderably deprefled beneath the Bog of Allen. 



Hence it appears, that in a foutherly dire(flion as far as Waterford ; eafterly, to 

 Dublin and Drogheda ; northerly, as far as Lough Allen ; and wefterly, to the ocean 

 at the mouth of the River Shannon ; the defcent of the kingdom is every where 

 from this exteuCve morafs. 



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