It is necessary to know the strength of wood used in the construction of stores, bridges, houses, etc.
Which is the most tenacious of metals?
Iron is the most tenacious of metals.
How is this principle in iron made useful?
It is useful in the construction of suspension bridges, and in very many other ways.
Can iron be drawn into wire?
Yes; iron can be drawn into wire.
What is this property of being drawn into wire called?
It is called Ductility.
Which are the most ductile of metals?