You may find this site of some use as it details some of the changes in the rules since the game came into being in 1895 -
http://websites.sportstg.com/assoc_...ID=175912&news_task=DETAIL&articleID=15492573
In terms of scrums, in 1931 the rule became that the "defending" teams half fed the scrum whilst the "attacking" team had the loose head (defending and attacking are defined in the laws of the game). This lasted unmodified until 1963 when the non-offending team given the feed and loose-head for scrums from penalties (including after kick to touch). This then saw a final change in 1982 when it became that for all scrums the non-offending team would be given the loose head and the feed.
Don't forget, with the introduction of limited tackle football in 1967 and until the introduction of the handover rule in 1989, if you were caught in possession at the end of your tackle count it would see a scrum. That was why many teams started kicking for touch on the last tackle as they had some chance of regaining possession at the resultant scrum.