[Bell Historians] PItch of bells

[Carl S Zimmerman]

A very timely question & answer! Last Saturday, the post-Congress 
(think AGM) tour of the Guild of Carillonneurs in North America 
visited the World Peace Bell in Newport, Kentucky. As you probably 
know, it is the world's heaviest swinging bell. The reported pitch 
is very slightly sharp of A, an octave and a third below middle C. 
But to my aging ears, the predominant frequency appeared to be D 
above middle C, an octave and a fourth above the strike tone. In 
fact, this virtual pitch seemed to be so strong that I could only 
distinguish it and the strike tone, not any of the other partial 
tones which should have been in range--very strange!

It occurs to me that this same phenomenon may have been the cause of 
the problems which Cyril Johnston had in casting the bourdon for 
Riverside Church in New York City. At the Congress, Jill Johnston 
read to us a chapter from her forthcoming book about her father and 
his work. She related how Frederick C. Mayer, carillon consultant to 
John D. Rockefeller Jr. on that project, rejected the first and 
second castings because the bells had a predominant fourth instead of 
the desired minor third. Ultimately the third casting was also 
rejected, and the project reverted to the first casting, which now 
hangs in Riverside Church. The turmoil of those rejections took its 
toll on Cyril Johnston, and it was during this time that Jill was 
conceived. I'll leave the rest of that fascinating story to Jill and 
her book. But it is interesting to speculate whether Mayer was being 
deceived by his own ears, and whether a modern frequency analysis (a 
la Bill H) would have given different results and saved Cyril some 
major headaches.

Returning to the World Peace Bell, what you probably don't know is 
that it weighs considerably more than the 66,000 lbs which has 
heretofore been advertised. That story, as told to me by Philippe 
Paccard, is also fascinating. It seems that at the time the WPB was 
being planned for completion to ring in the new millenium, another 
project for the "world's largest swinging bell" was being bruited 
about Paris. To finesse that, Verdin and Paccard gave out that the 
WPB was being planned for 30 metric tons (about 66,000 lbs), but 
actually they were planning for 33 metric tons. In the end, the 
Paris project fell through, and the finished WPB (hung as cast, 
untuned) weighed out at 33385 kg (slightly over 73,000 lbs) before 
shipping. With clapper and yoke, the total swinging weight is about 
104,000 lbs.

Incidentally, the clapper of thw WPB is a story in itself. The 
original (and extremely grandiose) plan was to hang this bell at 
about 200 ft altitude in a 2000 foot tall tower, surrounded by a 
90-bell carillon. It would have had the conventional falling 
clapper, and would have been audible for about 20 miles. However, 
the escalating cost of all aspects of the project meant that the 
planned tower wasn't built, and the WPB is hung only 35 feet above 
ground in a very squat structure. To use a falling clapper at this 
low altitude would have caused major damage to the hearing of people 
nearby, so Paccard switched to a counterbalanced "flying" clapper. 
With the counterbalance, the weight of this assembly is about 6 tons. 
When the swinging motor is turned on, the clapper begins to strike 
after only 6 oscillations, and the bell swings up no more than 45 
degrees in either direction. It is so well balanced that after it 
stops sounding (but keeps swinging), a visitor on the viewing 
platform can give it a push (quite safely, I assure you!) to make it 
strike once more. By the way, WI enthusiasts will be pleased to hear 
that this clapper is made of wrought iron. Paccard had great 
difficulty finding in France an ironworks with large enough forge 
capacity to make it; such firms are about as uncommon as 
bellfoundries these days.

After leaving the WPB, we visited Verdin's factory in Cincinnati, 
where thay had made the drop hammer by which this bell can be tolled 
(cast iron semi-conical hammer head made by a subcontractor), and 
finished the tour at the bellfoundry of Meeks & Watson, where we saw 
two small carillon bells being cast. But that's a story for another 
time.


At 08:27 +0000 2003/06/24, Bill Hibbert wrote:
>Chris Pickford:
>
>> "why can one always hear a strong fourth in big bells?"
>
>This is a virtual pitch, not a real partial, and arises because the
>ear is presented with several harmonic series and picks out one based
>on a harmonic higher than the nominal. The reason why we hear big
>bells, normal-sized bells and little bells differently is down to the
>ear's differing sensitivity to different frequencies. Ears are most
>sensitive to frequencies from about 1 kHz to 3 kHz and so we tend to
>hear a note between 500 and 1500 Hz, roughly, whatever the size of
>bell, if there is a harmonic series present to give a suitable
>virtual pitch.