317 
THE GREAT EXHIBITION BUILDINGS. 
BY WILLIAM FAIRBAIRN, LL.D., F.R.S., ETC., PRESIDENT OF THE 
BRITISH ASSOCIATION FOE THE ADVANCEMENT OF SCIENCE, ETC. 
T HE introduction of the use of iron in buildings has been 
a great desideratum for the last twenty years. For nearly a 
century, non has been employed in the construction of steam- 
engines and machinery ; and as improvements have from time 
to time been made in its manufacture, and confidence has been 
gained through experience in its use, it has gradually usurped 
the place of other materials in millwork, in shipbuilding, and 
for bridges. But its application to dwelling-houses and public 
buildings has been retarded by a want of the requisite know- 
ledge on the part of architects and builders, and a determina- 
tion in many quarters to resist its introduction as an innovation 
upon the good old practice of employing brick, stone, and 
timber, for such purposes. 
To ensure economy and success in the introduction of iron as 
a building material, the architect should make himself ac- 
quainted with its properties in its cast and malleable state, and 
he must commit to memory certain facts which bear upon the 
comparative resisting powers of these two materials under 
various kinds of strain. 
An example of the knowledge which is indispensable to 
architects and builders desirous to be considered proficient, 
will be found in the following data : — 
Tensile Strength Compressive Strength Transverse Strength 
per square inch in lbs. per square inch in lbs. per square inch in lbs. 
Cast Iron 16,500 112,000 40,000 
Wrought Iron ... 51,000 38,000 42,000 
Thus, it will be observed, that whilst the tensile strength of 
wrought-iron is three times as great as that of the cast metal, 
its resistance to crashing is only about one-third as great ; 
and these facts point to the effective and economical employ- 
ment of wrought-iron as ties, and in similar cases where tensile 
forces have to be resisted, and to the use of cast-iron for columns 
and framework, where the desideratum is to withstand the 
power of compression. 
Again, the architect must be aware of the different arrange- 
