Now those are some beauties.
http://bibliodyssey.blogspot.com/2010/09/locomotive-drawings.html
"The William Halsey Locomotive Drawing Collection contains 84 watercolor drawings by William Halsey (born ca. 1845- died ca. 1900), a railroad enthusiast probably working in the New York region as early as 1863 until the 1890s. […]
A significant aspect of the drawings is the record of colors and paint schemes used at the time. Some of these drawings represent the only records of this form of applied decorative railroad art to survive. As a group, the engines display a wide range of colors, and frequently display schemes indicative of locomotive builders or the shop’s style that maintained them."
The William Halsey Locomotive Drawing Collection is available from Southern Methodist University in Dallas.
http://digitalcollections.smu.edu/all/cul/hal/