When I started volunteering at DeBence, it was working on a Wurlitzer 105 Band Organ, made in 1928. Among other problems, it needed to be tuned. My background as a mechanical engineer made this look straightforward to me. If you know the length of a pipe, you know what frequency it will sound. Well, not really. The formula has a fudge factor which seems to vary from one situation to another. In spite of what Ralph Nader thinks, engineering is not really a completely exact science. Tuning is not really an Engineering problem.
The next revelation was that there was and is no real standard for what frequency a given note is suppose to be.
My first reference check with ANSI said A is supposed to be 440Hz. Well, it turns out that is not necessarily true or universally accepted in all situations. It was usually 432 Hz(the French standard from the 1860s) in the past.
We got to work on a Frati built about 1900 in Germany and working backwards from the way it tuned, it seems A was tuned to about 390 on that organ. European orchestras today, sometimes tune about 440 to get a "brighter" sound.
One reference said German (German Natural History Society, 1834) and American standard setting bodies wanted A=440 in the 1920s, but could not get anyone else to agree. The A=440 standard was adopted by the Musical Industries Chamber of Commerce in 1925.
Most official standards seem to date from the 1930s. The ANSI standard A=440, came out in 1936. The American Federation of Musicians agreed with it. At that point WWV started broadcasting an A=440 tone on the hour, so we could all get with the standard. In 1955, ISO 16 was released calling for A=440.
The whole subject is further confused by deciding what temperature that standard is set at. J.C. Deagan (zylophones) is quoted as saying A=435 was set at 59 degrees F and if you bring that pitch to 70 degrees F you get A=440.
We have noticed that an orchestrion with piano and pipes tuned at any standard, will go out of tune with itself as the temperature changes, because the pipes and piano change pitch differently.
Today, there is general agreement that various pitches are appropriate for different performances.
1) American and UK concert pitch is usually A=440 and that is normally indoors.
2) European concert pitch is between A=440 and A=444, depending on the conductor.
3) Baroque music is often played at A=415, unless it is 430 or in some cases 466.
What it boils down to,isyou can tune to whatever you think sounds best for what you are playing and someone will have a different opinion; but nobody can definitely say you are wrong. If the instrument is tuned with itself, most people will thing it sounds fine.