HE PROPERALES Of BULLDING STONES, ETC. 183 
The manner of dressing a stone also influences in a small way 
the length of its life. A stone which has polished surfaces sheds 
water much more quickly and is disintegrated much more slowly 
than one with rough surfaces. The stone with rough surfaces 
has many crannies and crevices, in which the water collects and 
is finally absorbed. Sandstone which has been hammer-dressed 
is liable at first to disintegrate faster than that which has been 
sawed, due to a weakening of the cement by the impact of the 
hammer. In general, it may be said that polished and sawn 
surfaces shed water most readily, while those that are rock-faced 
or hammer-dressed, on account of their rough exterior, absorb 
a considerably larger percentage of the water which falls on 
their surfaces. 
Before a stone is used in the construction of a building it is 
safer to have at least the water of saturation driven off. Asa 
rule quarrymen are acquainted with the effects of frost upon 
stone in which the water of saturation still remains, and observe 
the necessary precautions. There are quarrymen, however, inter- 
ested solely in the disposition of their stock, who impose upon 
the ignorance of the public by selling stone which has not been 
seasoned. Stone should be seasoned not only to escape the 
danger from freezing, but also to insure safety in handling and 
laying. 
The exfoliation of sandstone in the large eastern cities has 
been mainly attributed to the fact that much of the stone has been 
laid on edge instead of on the bed. Laying stone on edge has 
been practiced at all times, owing to the greater readiness 
with which stratified or schistose rocks can be dressed along 
thewbed, The greatest tendency, to) lay stone on edge ‘is 
encountered in veneer work, but is occasionally met with in 
heavy masonry. 
If the parting planes, which ordinarily furnish the easiest 
paths for percolating waters, are normal or inclined to the sur- 
face of the earth, they will admit the passage of water much 
more readily than if they are parallel. Thus if a block of stone 
is placed on edge in a wall, there will be greater danger from the 
