334 SIGIUES, SHOU SIL CIDIEIN HSS 
judgment and experience of the observer. They lack a definite- 
ness and certainty which can only be supplied by the laboratory 
tests. No one of these should be considered sufficient in itself, 
but each should be used in conjunction with the other two. 
QUARRY OBSERVATIONS 
Several important conclusions may result from quarry obser- 
vations which cannot be reached through an examination of 
buildings or selected samples in the laboratory. Chief among 
these may be mentioned: (1) the probable injury to the stone 
from quarrying, handling, and dressing; (2) the capacity of the 
quarry to furnish as needed the required quantity of stone of the 
desired quality; (3) the uniformity in color and mineralogical 
composition, and the apparent uniformity in strength, hardness, — 
elasticity, and porosity. 
Stone is often more or less injured through improper methods 
of quarrying and dressing or careless handling, as explained in 
the previous paper.t*. One can become familiar with the methods 
employed in quarrying the stone only by visiting the quarry 
where the work is being carried on. 
The knowledge that a quarry has the capacity to furnish as 
needed the required quantity of stone of the desired quality is 
an important matter. A quarry is sometimes poorly equipped 
with machinery; men may be scarce; orders for stone may be 
plentiful; and as a consequence inferior stone is placed upon the 
market for the better grade. The situation of the quarry in 
these respects can be best determined by an examination of the 
quarry and its equipment. 
The uniformity in the color of the stone can be quickly 
determined by an examination of the quarry. If the stone dif- 
fers in color at different horizons, or in different parts of the 
quarry, precautions can be taken in the specifications to insure 
the receipt of stone of a uniform color by-designating that it be 
taken from a definite part of the quarry. 
tJour. GEOL., Vol. III, No. 2, pp. 181-184. 
