if you are looking for info about northern european cannons look at this
www.arkeliet.net its mostly norwegian , swedish , danish and german models .
but its very very interesting. oldest artillery handbook is dated 1698
when you come there , look for the word : bildearkiv
its located in the right upper part of your screen, leftclick at that word and you will find yourself in heaven
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then just choose the book of your choice, left click on it and see all pages in it
all drawings are enlargeable, now you dont need to guess anymore of how things looked .
ok I know I have mentioned this address before in an post , but I belive its that much important that it need its own .
hope you will write down your comments here after you been there
here I just attach an sample from there