1885.] NEW YORK ACADEMY OF SCIENCES. 61 



that " then " will be too Lite, for there is no known process that 

 will clean and restore a white or light-colored brick front to its 

 original appearance. It is permanently ruined. ''Prevention is 

 better tlian cure," for in tliis case, if a decent-looking wall is de- 

 sired, after it lias stained, it must be coated with })aint or 

 color, and that forever prevents the brickwork from being seen 

 again, except in spots, in a dilapidated condition, where the paint 

 ])eels off. 



The d iscoloration of the terra cotta of the new New York Cotton 

 Exchange is rapidly taking place in spite of its coatings of lin- 

 seed oil, and its liglit yellow bricks will ore long look like those 

 of the building on the opposite corner, William and Beaver 

 streets, and those of the " Post" Building, on Beaver street and 

 Exchange place, which are stained beyond the possibility of re- 

 storation. 



A very important consideration with an architect, in designing 

 a good building, is color — the pro[)er blending of shades. But 

 of what use is it for him to be so careful in selecting brick and 

 stone of certain tints, and to see that the builder and mason exe- 

 cute good clean work, when in a few montlis after it is finished 

 the whole of the beauty is completely marred by unsightly dis- 

 colorations. 



If It is worth while to spend time and money, and to take so 

 much care in designing and erecting a substantial and handsome 

 building, surely it is wise to spend a further comparatively small 

 amount to permanen'tly preserve the whole from the ruinous 

 effects of the weather, which will surely follow exposure. 



Let us now briefly consider in this connection a few of the 

 stones used in New York buildings. 



Brownstone is a popular stone, and deservedly so. There is a 

 very substantial look about a brownstone house. The stone has a 

 beautiful grain and si)arkle, and does not, on account of its color, 

 readily show the weather stains which are sure to occur in a city. 

 But the chief objection to it is its liability to decay. It absorbs 

 water freely, and then the frost quickly disintegrates it. If 

 bedded on a dry, water-proof foundation, and protected from the 

 action of water and frost, there is no reason why it should not 

 remain sound and good for an indefinite time, and the above 

 objection to its use would no longer exist. 



The entrance to the Greenwood Cemetery, at Brooklyn, a fine 

 brownstone structure, is badly decayed. It is said that many 

 things have been tried to save it, linseed oil and sundry solutions, 

 but all useless, none lasting over a year; and the beautifully 

 carved work, erected at a great cost, seems doomed. 



The Carlisle or Scotch red sandstone, though very beautiful in 

 its color and grain, is probably the most absorbent of all the 



