Then divide a million by that number and you have a rough calculation of how many machines they made per year. The most common way of dating them is spotting an advert that says 'This year we will have made a million machines!' - take the year the company started away from the year of the million sales announcement. When I contacted John Langdon about my Gritzner, although he said he didn't know a lot about German sewing machines, he sent me this on dating mine: 'German machines were not well documented at all. › ★ Gritzner Durlach Sewing Machine Serial Numbers
