[78-L] Historical Nomenclature

[Harold Aherne]

The LP thread got me to looking up when the phrase "First World War" was first used, and I can trace it to at least 14 November 1920. The NYT of that day published an article called "Farmers Warned Not to Hold Wheat", in which the Times noted how cynical that particular phrase seemed, although it was eventually used with greater frequency. 
 
All right, so when did "78" come to be used as a noun?
 
-Harold