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 unfitted for outdoor work in that vicin- 

 ity. These results are greatly in exaggeration of what takes place in 

 our own cemeteries. Professor Julien states that in the city cemeteries 

 about ISTew York tlie polish on marble tombstones often survives for ten 

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

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

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

 inscriptions dating back to the latter part of the eighteenth century are 

 illegible, he has never seen the same effect produced in suburban cem- 

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

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

 and cities of New England marble tombstones will retain their polish 

 for a period of ten or fifteen years and up to thirty or thirty-five pre- 

 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 which particles of 

 dirt become lodged or lichens take root, giving it a dirty and unkempt 

 appearance.* 



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 

 noncrystalline, compact, and homogeneous limestone is probably as 

 little affected by frost as are the granites. Very many of the lime- 

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

 means sufficiently non-absorbent to protect them from injury by freez- 

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

 disintegration going on more rapidly in some layers than others, thus 

 producing rough and unsightly walls. Professor Winch ell, writing on 

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

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

 aspect when dressed under the hammer, 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 protected from the weather the shale will endure and act as a 

 strong filling for the frame-work of calcareous matter for a long time ; 

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

 thawing, it begins to crumble 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 subcrystalliue limestones the argillaceous matter, instead 

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



* The line grained saccharoidal marbles used for statuary are even less durable, and 

 in extreme cases have shown serious disintegration at the end of three or four years 

 exposure. 



t Preliminary Report on Building-stonca, etc., 1880, p. 12. 



\ Report on Building-stones, p. 30. 



