From Peter Daymond-King, Helensville, New Zealand
I was surprised to read that “in the early 20th century there was no seismology [and] no accurate location data for earthquakes” (25 November 2017, p 40).
We may discount the seismometer developed by Zhang Heng in AD 132 because we don't understand how it worked (see 3 December 2016, p 42). But back in 1969, James Dewey and Perry Byerly listed, at my rough count, at least 15 earthquake recording instruments developed between 1703 and 1889 (Bulletin of the Seismological Society of America, bit.ly/ns-seismo). And the Seismological Society of Japan was founded in 1880.
