Bill O-"The 231 was recorded with a modified 3-cup, not a pitot. Well, it worked on the same principal as a 3-cup."
The anemometer that was used to measure the 231 mph wind was known as 'old No. 2' and it is located in the museum on the summit. It wasn't a 3 cup but about a 6" diameter cylinder or drum, maybe 2" thick, with 6 'scoops' on its diameter to catch the wind. The wind speed was measured by timing 'clicks' from electrical contact closures made every so many revolutions of the drum. There is a photo of this anemometer (between p170 and p171) in 'The Worst Weather on Earth' published by the MWO in 1991.