The words âat least 17 years of age and *â*â* under 45 years of ageâ are substituted for the words âwho shall be more than seventeen years of age and *â*â* not more than forty-five years of ageâ.
Steel is cheaper, and brass is more expensive, and not much of a structural material. Brass is a tensile metal, and has a great ability to bend. It is used to make bearings, valves and moving parts, because it does not break easily. Steel, on the contrary, is difficult to cast, and quite difficult to work with in small machines.
Brass is a metal that consists of both copper and zinc. Bronze is a metal that consists of copper and tin. Bronze is the most popular metal for cast metal sculptures or bronze sculptures. Common bronze alloys often have the unusual and very desirable property of expanding slightly just before they set, thus filling the finest details of a mold.