In article ,
Paul Crabtree writes:

Can we trust records from 1659 !! - what thermometer were they using ! were
they calibrated !

Just a thought

Professor Gordon Manley spent many years researching these early
records, and he calibrated them so meticulously that I'd sooner rely on
them than on some current ones.
--
John Hall
"If a man will begin with certainties, he shall end in doubts;
but if he will be content to begin with doubts,
he shall end in certainties." Francis Bacon (1561-1626)