What was this Book Used for?

[nw-mailing-list at nwhs.org]

Hello,
My Second Cousin Purchased Book at a recent Train Show we both have N&W 
in out blood which would explain my interest in the book along with his,
The following link is to some photos of the book, 
http://members.trainorders.com/trainman51/book/index.htm neither my 2nd 
Cousin nor I can figure out what it was used for I only 19 years of age 
have no clue of what existed in 1969 nor did i grow up with N&W but 
NS...But we both have N&W in out blood. Could somebody offer an 
explanation to what the book was used for?

Sincerely,
Nathan Simmons