Book excerpt: Steam locomotives dominated the railways from the 1820s through the 1960s. Today almost all of them have been replaced with electric and diesel engines, yet the fascination surrounding steam-powered trains has not dwindled. A diverse community of enthusiasts--from mechanics to teachers to lawyers--have taken up the hobby of building and running steam locomotives in their own backyards. Drawing on the author's extensive experience and research, this guide covers the materials, tools, skills and technical information needed to get started or to improve an existing design.