Felt & Tarrant sterling models

From: C. B. Dawson
Email: cbkiteflyer@yahoo.com


I have a question about the F&T Sterling model comptometers: I've seen pictures of some with an extra column of blue keys on the right to handle farthings (quarter pence) and some without this column. How was this difference accounted for in the model designation? (E.G. model J vs. model J-1, or whatever...?) Thanks in advance. CB