Bell tuning before tuning forks

[Bill Hibbert]

Does anyone know of reference material I could read explaining how 
(UK) bellfounders tuned their bells before the introduction of the 
tuning fork? I know about the Hemony bars, I have read Elphick, and 
have consulted the various reading lists and bibliographies, but have 
not yet found any detailed description of how tuning was done.

I am particularly interested to know what pitch references were used 
and how the bells were compared against them.

Any help gratefully accepted.

Bill H