Optimal Line Length
http://www.humanfactors.com/downloads/nov02.asp#oll

Bailey, Robert
Human Factors International
2002

Abstract:

What can we conclude when users are reading prose text from monitors? Users tend to read faster if the line lengths are longer (up to 10 inches). If the line lengths are too short (2.5 inches or less) it may impede rapid reading. Finally, users tend to prefer lines that are moderately long (4 to 5 inches).