The number of degrees of a circle that the earth will "twist"
under a pendulum in 24 hours at any given latitude (n)
may be determined by the following formula:
Latitude = angular distance of a place from the equator
At San Francisco
Latitude - California Academy of Sciences = 37° 46.2'
Sin Latitude = .6125
n = 220.5° in 24 hours
1 Revolution = 39.18 hrs.