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On 2014, Dec 05, , at 11:02, John Denker <jsd@av8n.com> wrote:
1) It is all-too-easy to fudge the data inadvertently --
even if you have the best of intentions -- perhaps by
"pruning" the outliers. Don't do it!
In fitting the decay (or rise) to equilibrium, after a quake, of the amplitude of a rather sophisticated clock,**I eliminated two or three “outliers” I justify removing outliers if one may ascribe their cause, in this case aftershocks. I think a very good assumption.
bc also separately fitted the before and somewhat after the v. sl. after shock, also.
**I suspect nearly the best mechanical one invented — better than the Shortt? The gravity arms contact the pallets perpendicularly. The only source of escapement dissipation is the gravity arms’ pivot. Tho the pendulum operates in the quadratic regime, its Q is high because the bob weighs ~ 175 pounds!] ["Big Ben’s” is 330# (600kg)] Also their supports are very rigid. Parliament clock’s is five tonnes. The SB clock view:
The clock’s free Q is 10k and running Q, likely, only sl. less, because of its very sophisticated escapement.— the same design as the Denison-Airy’s clock in the Houses of Parliament (controls the Big Ben bell, inter alia).
Santa Barbara Courthouse Clock
http://www.bmumford.com/mset/courthouse/
p.s. I suspect the pivot friction doesn’t reduce the Q only the amount of force applied to the pallets, which is the pendulum’s rod.