CHAPTER XIV 
BUILDING STONES AND ROAD METALS 
I. BuiLping StoNEg! 
BuiLpiNnG stone may appear so durable that it might be 
expected to last for ever; yet some stone buildings decay 
with deplorable rapidity. The outer stone of most of West- 
minster Abbey is said to have been replaced five times. 
The British House of Parliament, built in 1840-50 of stone 
recommended by a Royal Commission whose report (1830) 
was for long the standard text-book on British building stones, 
has crumbled so fast that its ornament has been partly 
replaced by cast-iron, and the Members of Parliament were 
warned in 1925 not to stand within 3 feet of the walls to avoid 
falling fragments. The quickness with which stones decay 
may be realized in any old churchyard, for it is rare to find 
an intelligible inscription on a tombstone more than 200 
years old, unless it has been recut. Poor stone is less durable 
than good timber. Most of the buildings that have lasted 
six or seven centuries are churches, which were built by 
religious fraternities who would have regarded the use of 
inferior material as sacrilege. 
Cavuszs oF DEcay—The decay of building stone is primarily 
due to the entrance of water, which weakens or dissolves the 
cement and introduces material that, on solidification, dis- 
integrates the stone. The early builders therefore designed 
projecting dripstones, string-courses, and gargoyles to throw 
the rainwater off the building. The injurious effect of 
moisture is often shown by the decay of the under surface 
of projecting stone, and in the lower part of a wall which 
lds ; he testing 
J. A. Howe, The Geology of Building Stones, 1910; for t : 
of La 7. Hirschwald, il bautochnischen Gesteinsprifing, 
Berlin, 1912,