The small sizes in regular weight and width were released in the 1920s. In the early 1950s Ludlow added larger sizes and cut Condensed and Extra Condensed. From 1956–69 Ludlow expanded the family to 20 members, with Middleton contributing to many of the styles. [McGrew]
The family members vary widely in style, some close to News and Alternate Gothics, others similar to Akzidenz-Grotesk, Folio (Bold/Heavy Condensed) and Helvetica (Medium-Extended).
No digital version available, but Notary is explicitly based on the standard width.