JOURNAL 



of 



NATURAL PHILOSOPHY, CHEMISTRY, 



THE ARTS- 



jUNjSy isn* 



ARTICLE I. 



iy^scrtpiion of a Method of Roofing Buildings securely with 

 Flagstones, By Righard Lovell Edgeworth, Es<l» 

 F. B. 6. M. R. L A. 



To Mr. NICHOLSON. ' 



SIR, 



Jj^ Had occasion some time ago to roof a large building in 

 an uncommon manner. I send you an account of it; as it 

 has succeeded; and, as I believe, it may be useful in many 

 places where slates and tiles are not to be had. 



The gaol of Longford, in Ireland, which was built about Gaol of Lorty* 

 twenty years ago, was covered with a circular arch of bricks; ^o^d roof«<i 

 upon wliich broad flat stones, commonly called flags in this 

 country, were laid with the best mortar that could be pro- 

 cured ; these thin stones or flags were placed side by side ; 

 the lateral joints were filled up with mortar; and ajl the / 



courses, as they descended, lapped over each other about 

 two inches. After a short time the sun and frost cracked P«nct/*te4bj 

 the mortar between the joints, and the rain found a way ^* 

 into every part of the building. 



Vol. XXiX.No.l32.— Jvj(E,1811. Q Op« 



