Trans. N. Y. Ac. Sci. 136 Apr. 30, 



island, with trimmings, string-pieces, etc., of brown stone, the latter, as 

 usual, being in a state of decay. On the west front, the gneiss is in 

 excellent condition, occurring in small blocks, mostly laid on tbe bed- 

 ding-plane. In the south front, many of the quoins are set on edge and 

 are much decayed along the joints, sometimes with splitting or exfolia- 

 tion, fracture of corners, and irregular chipping out of the surface to the 

 depth of one-half to one inch below the level of the projecting cement- 

 joints. 



GENERAL CONCLUSIONS. 



If a rough estunate be desired, founded merely on these observations, 

 of the comparative durability of the common varieties of building- 

 stone, used in New York city and vicinity, there may be found some 

 truth in the following approximative figures for the " life " of each 

 stone, signifying by that term, without regard to discoloration or other 

 objectionable qualities, merely the period after which the incipient decay 

 of the variety becomes sufficiently offensive to the eye to demand 

 repair or renewal. 



Life, in Years. 



Coarse brownstone 5-i 5 



Laminated fine brownsto7ie , 20-50 



Compact fine broivnstone ico-200 



Bluestone , Untried, probably centuries. 



Nova Scotia stone Untried, perhaps 50-200 



OJiio sandstone, (best silicious vaiiety), perhaps from i to many centuries. 



Limestone, coarse fossiliferous 20-40 



Limestone, fine oolitic (French) 30-40 



" " (American) Untried here. 



Marble (Dolomyte,) coarse 40 



" " fine 60-80 



Marble, fine 50-200 



Granyte 7 5-200 



Gneiss 50 years to B'lany centuries. 



Within a very few years past, it has become frequent to introduce 

 rude varieties of rusticated work into the masonry of buildings in this 

 city, or to leave the stone rough and undressed in huge blocks, espe- 

 cially in the basement or lowest stories, where it is under close and 

 continuous inspection, and the results of its decay will be disguised by 

 its original rough surface. Although there are certain large buildings 

 in which such a massive treatment of stone may be appropiiate, its 

 common use, with stones of known feebleness or lack of durability, is a 

 disingenuous evasion of responsibility and a mere confession of ignor- 

 ance, want of enterprise, and despair, in regard to the proper selection 

 of buildmg material and in regard to its protection. 



Finally, it may be pointed out that many of the best building stones 

 of the country have never yet been brought into this city ; e.o^., silicious 



