.255 and .275 Jefferey Rook dates

Does anyone know the dates the .255 and .275 Jefferey Rook cartridges were introduced?
Thanks,
Joel

1908 and 1910 respectively is what I have them down as. Again as last post, these are from my notes with sources lost. I am sure others will confirm or edit.

Thanks! I’ll used these dates for now.
Joel