A 'jack' was someone who had completed part (I think two years) of his seven-year apprenticeship, so was semi-skilled. He had not become a 'master' by completing a 'masterpiece' in his final year that would be judged by the other masters of the trade as proving that he was now fully competent in that trade.
By clicking on the User Name, you will requery the forum for that user. You will see everything that he or she has posted with that Mudcat name.
By clicking on the Thread Name, you will be sent to the Forum on that thread as if you selected it from the main Mudcat Forum page.
* Click on the linked number with * to view the thread split into pages (click "d" for chronologically descending).
By clicking on the Subject, you will also go to the thread as if you selected it from the original Forum page, but also go directly to that particular message.
By clicking on the Date (Posted), you will dig out every message posted that day.