Hi Topmapman and welcome to the forum

The CNR perfins you mentioned were used by the Canadian National Railways. The Canadian Northern Railway also used a perfin similar to that of the "National" one.
They can be found reading straight across or reading down. This was done mainly to identify the origin of the office of use within the Canadian National Railway system because they had offices across Canada.
All of these perfins from the CNR can be found from stamps of 1903 to 1983. The Winnipeg office used them the longest.
It is also interesting to note that there are CNR perfins on British stamps (and Newfoundland as well because it was not yet a province) because the CNR had offices in the UK as well.
Hope this helps?
Chimo
Bujutsu