1883. Y3 Trans. N. Y. Ac. Sci\ 



For side A'alks and curb-stones, the material generally employed is 

 the flagstone, a thinly bedded blue sandstone or graywacke from the 

 interior of the S'ate, the Catskill Mountains, and from Pennsylvania ; 

 also, granyte, chiefly from Maine. In the older street?, a mica-slate 

 fiom Bolton, Conn , and micaceous slaly gneiss from Haddam. Conn., 

 were once largely used, and may still be occasionally observed in 

 scattered slabs. 



Additional facts were given concerning the ruling prices for the va- 

 rieties of stone, tables presenting all the determinations obtainable, in 

 reference to the crushing strength of the varieties used in New Yoik, 

 lists of the dealers in building and ornamental stones, etc. 



III. Durability of Building-Stcnes, in New Yoik City and vicinity. 



All varieties of soft, porous and untested stones are bemg hurried 

 into the masonry of the buildings of New York Ciiy and its vicinity. 

 On many of them the ravages of the weather and the need of the re- 

 pairer are apparent within five years after their erection, and a resist- 

 ance to much decay for twenty or thirty years is usually' considered 

 wonderful and perfectly satisfactory. 



Notwithstanding the general injury to the appearance of the rotten 

 stone, and the enormous losses annually involved in the extensive re- 

 pairs, painting, or demolition, little concern is yet manitested by ei her 

 architects, builders, or house owners. Hardly any department of 

 technical science is so much neglected as that which embraces the 

 study of the nature of stone, and all the varied resources of lithol- 

 ogy in chemical, microscopic il, and physical methods of investigation,, 

 wonderfully developed within the last quarter century, have never yet 

 been properly applied to the selection and protection of stone, as used 

 for building purposes. Much alarm has been caused abroad in the 

 rapid decay and fast appr)aching ruin of the mrst important monu- 

 ments, cathedrals, and public buildings, but in many instances the 

 means have been found for their artificial protection, e.i:;., the Louvre 

 and many palaces in and near Paris, France, St. Charles church in 

 Vienna, Austria, the Houses of Parliament, etc., in London, England,, 

 etc. 



In New York, the Commissioners of the Croton Aqueduct Depart- 

 ment complained, twenty years ago, of the crumbling away of varieties 

 of the gneiss used in embankments ; the marbles of Italy, Vermont, 

 and of Westchester County, soon be.come discolored, are now all more 

 or less pitted or softened upon the surface {e.g., the U. S. Treasury),, 

 and are not likely to last a century in satisfactory condition {e.g., the 

 U. S. Hotel); the coarser brown sandstones are exfoliating in the most 

 offensive way throughout all of our older streets and in many of the 



