BUILDING AND ORNAMENTAL STONES. 343 



a climate as that of Edinburgh lost their polish after an exposure of 

 but a year or two and became entirely destroyed in less than a century; 

 hence that the stone was quite uniltted for outdoor work in that vicin- 

 ity. These results are ,qrcatly in exaggeration of what takes place in 

 ourown cemeteries. Professor Julieu states that in the city cemeteries 

 about Kew York the polish on marble tombstones often survives forten 

 years, and in protected places, as near tlie ground in suburban ceme- 

 teries, for half a century. lie further states tliat while of the tomb- 

 stones in St. Paul's chuicliyard in New York City, about one-tenth of the 

 inscriptions dating back to the latter i)art of the eigliteenth century are 

 illegible, he has lU'ver seen the sanu' <'ffecC i)roduced in suburban cem- 

 eteries in the same length of time. The author's own observations on 

 the subject are to the ellxHtt that in the cemeteries of the smaller towns 

 and cities of New England marble tombstones will retain their i»olish 

 for a jjciiod of ten or fifteen years and i\\) to thiity or thirty-five ])re- 

 sent no sign of disintegration of a very serious nature. Beyond this 

 time, however, the surface becomes rough and granular and the edges 

 of the stone may be found filled with fine rifts into whicli particles of 

 dii't become lodged or lichens take root, giving it a dirty and unkempt 

 ap]»eaiance.* 



Such stone are frequently taken down, rehoned and polished, and again 

 set up to do duty for another term of years. A closely crystalline or 

 non-crystalline, comi)act, and homogeneous limestone is probably as 

 little alfected by frost as are the granites. Very nniny of the lime- 

 stones and dolomites used for ordinary building are, however, by no 

 nu'ans sulficiently non-absorbent to protect them from injury by freez- 

 ing, nor are they sufliciently uniform in texture to weather evenly, the 

 disintegi'ation going on more rapidly in some layers than others, thus 

 producing rough and unsightly walls. Professor Winchell, writing on 

 tlu^ weathering of the Trenton limestone used at Saint Paul and Min- 

 neapolis, says :t "The stone itself has an attractive and substantial 

 aspect when dressed under the hauuner, the variegations due to the 

 alternating shaly and limy parts giving the face a clouded appearance, 

 as of gray marble, without being susceptible of a uniform polish. 

 Where ])rotected from the weather the shale will endure and act as a 

 strong fdling for the frame-woik of calcareous nuitter for a long time ; 

 but under the vicissitudes of moisture and dryness, and of freezing and 

 thawing, it begins to crumbh; out in a few years. This result is visible 

 in some of the older buildings, both in Saint Paul and Minneapolis." 

 Professor Hall, writing on rock weathering,^ says: "In the gray or 

 bluish gray subcrystalline limestones the argillaceous matter, instead 

 of being distributed throughout the mass, is usually present in the 



* The fine j^rained saccli.iroidal marbles used for statuary are even less durable, and 

 in extrcnio cases have shown serious disintei^ration at tlie end of three or four years 

 exposure. 



t Preliminary Report on Huildiuj5-stoue3, etc., I8H0, p. 1:5. 



t Report ou Buildiug-atoucs, p. IJG. 



