Change in foul ball rules

[snopes]

Comment: In baseball, I was told that the rules on a fair/foul ball were
changed so that any ball hit out of the park in fair territory and then
hooked foul was now a home run. Under the previous rules, it was a foul
ball. Had the new rule been in force during Babe Ruth's career, it was
estimated that he would have been credited with 50-75 more home runs.

[snopes]

As I recall, the change in game-winning home run rules cost Babe Ruth a few homers, but I don't think there were any changes in fair/foul rulings during his career.

[Mr. Furious]

It's not something that I'd ever heard of before, but it's mentioned in the ever-reliable Wikipedia, with no citation.

Also, until approximately that time, the ball had to not only go over the fence in fair territory, but to land in the bleachers in fair territory or to still be visibly fair when disappearing behind a wall. The rule stipulated "fair when last seen" by the umpires. Photos from that era in ballparks, such as the Polo Grounds and Yankee Stadium, show ropes strung from the foul poles to the back of the bleachers, or a second "foul pole" at the back of the bleachers, in a straight line with the foul line, as a visual aid for the umpire. Ballparks still use a visual aid much like the ropes; a net or screen attached to the foul poles on the fair side has replaced ropes. As with American football, where a touchdown once required a literal "touch down" of the ball in the end zone but now only requires the "breaking of the [vertical] plane" of the goal line, in baseball the ball need only "break the plane" of the fence in fair territory (unless the balls is caught by a player who is in play, in which case the batter is called out).

Babe Ruth's 60th home run in 1927 was somewhat controversial, because it landed barely in fair territory in the stands down the right field line. Ruth lost a number of home runs in his career due to the when-last-seen rule. Bill Jenkinson, in The Year Babe Ruth Hit 104 Home Runs, estimates that Ruth lost at least 50 and as many as 78 in his career due to this rule.

Again, though, this is Wikipedia and there is no citation listed.

[RealityChuck]

According to this site, the current rule on home runs was established in 1920. Babe Ruth had hit only 49 total home runs at the time (29 of those in 1919). It's unlikely he lost more than a half dozen home runs to this rule, if that many.

According to Ken Burns' Baseball documentary the original rule for a home run was that the ball would just need to roll into the crowd. So fans of the home team crowd would come forward to make the outfield shorter for their batters then back up for the visitors. I believe this was before Babe Ruth's time as most stadiums he played in had walls, but how many could he (or others, for that matter) have hit with that rule?