"When I considered the "present measurements" I did so based on publication of the listed yardages before the recent Amateur when the course was listed at around 6800 yards, if I recall correctly."
David,
That was a mistake. You neglected to consider unchanged holes and distances stated from tees that remain from the 1930 Amateur. The yardage used in the 2005 Amateur differs from the yardage prior to that only due to lengthening on holes 2,3,5,6,9,12,14,15,17 and 18. All of these holes and the unchanged holes retained the existing tees as used in the 1930 Amateur. The yardage I posted represents the yardage on the current scorecards, which were redone this year and are all of 4 days old.
The back tee on the 10th hole is the same as the one that existed in 1930 and 1924 prior to that. It did not exist in 1916. Nothing has been done to the 10th hole since 1930 except for the regrassing of the green, the work on the bunkers within the last 6-7 years and the installation of an XGD system.
What additional factual support are you looking for? I'm completely convinced of this and would welcome any findings of yours that correct my opinion.
The measurement you refer to on the 10th, as we have established several times, is dependent upon where the turn was taken for the approach shot. The yardage discrepancy is mostly, but not entirely, based upon that. Alan Wilson talked about how measurements are done on "a good many courses" in two articles in the USGA Green Section, on July 21, 1923 and March 24, 1924. Neither article identifies Merion as a specific example of one measurement manner or another. In the 1923 article, AW wanted to standardize the scorecard measurement from the middle tee to the middle of the green. I don't know why he didn't suggest measurements from the middle of each tee so that the scorecard would be accurate for all players and for handicapping purposes. In the 1924 article, Alan Wilson recommends using the contour method to measure as it is better for practical reasons. He goes on to state that for uphill holes, the contour method represents the playing yardage better than a measurement from middle of tee to middle of green (which he cites as the better method in the 1923 article). For dogleg holes and holes with long diagonal carries, AW recommended that the holes be measured along a line of play "which would be used by the standard good player--a man who could drive the ball 225 yards rather than a short hitter or a very long player--leaving an open angle into the green.