Old tuning forks, pitch standards

[Richard Moody]

For basic information  New Grove's  has an excellent article on tuning
forks.
A good original source are the Ellis appendices in Helmholtz,
_Sensation of Tone_  under the heading "A history of Pitch" or
something like that.
Britannica has a good mention.

14 cents sharp of A440 is 444 within one beat in 10.   ---ric


----- Original Message -----
From: Mike and Jane Spalding <mjbkspal@execpc.com>
To: <pianotech@ptg.org>
Sent: Sunday, August 19, 2001 11:19 PM
Subject: Old tuning forks, pitch standards


List,

Today an older gentleman at our church gave me 3 old tuning forks that
had belonged to his wifes uncle, a piano tuner.  I am curious to know
their approximate age, and also what, if anything, they tell us about
the history of pitch standards.

The largest, (and probably the youngest) fork is 125 mm overall
length, with tines about 5mm x 6mm.  It is stamped"DEAGAN  CHICAGO",
"A=440", "OFFICIAL PITCH A.F. OF M. 1917", and "ADOPTED BY U.S. GOVT.
1920".

The next smaller fork is 110mm overall, with tines about 4mm by 5mm.
It is stamped "INTERNATIONAL PITCH C 517.3" (which is the frequency of
C52 when A49 is at 435).

The smallest fork is the same length, 110mm, but the tine cross
section is 2mm by 5mm, and the 2mm dimenstion is very irregular as if
it had been shaped by hand.  Probably due to the irregular
cross-section and/or small size, it's sustain time is very short. It
is stamped "PHILHARMONIC", and "A".  This fork is about 16 cents sharp
of 440.

Are there any good written resources for learning more about the
history of these forks, or their makers?  Anybody out there old enough
to have personal knowledge?

thanks