1879.] on Bells. 107 



Olio and the same bell with a number of different clangs, eacli with its 

 scries of overtones, tlio overtones of the different clangs sometimes 

 overpowering each other, at others tones arc found in the bell re2)re- 

 scnting intervals less than a minor third, and producing beats, and at 

 the same time we get certain deep hums, which I believe must be due 

 to what in acoustics are called combination tones. Now obviously 

 what a bell aims at musically is one fundamental note, and the 

 problem is how to subordinate all other clangs, extingu'shing those 

 tones that are discordant, and subduing the overtones of the fun- 

 damental clang, so that none of them drown the desired note of the 

 bell. Thus when you strike the bell on the sound-bow you get one 

 definite note, varying in quality according to the number and propor- 

 tion of the overtones, varying also according to the character and 

 pitch of any other unextinguished clangs that may be present. 



I must content myself with pointing here to the elements of the 

 problems which can only be solved by experiment. The bell-founder 

 has, in a word, to contend first with different clangs, secondly with 

 loud overtones, thirdly with beats, and fourthly with combination 

 hums ; and the problem is how to obtain the presence in right j^ro- 

 portion of those tones he requires in order to produce the timbre of 

 his fundamental note, and how to extinguish those tones which 

 interfere with the supremacy or quality of his fundamental note. 



Now the Belgians have a summary way of settling all this. They 

 fix the note, and have a clear perception of the quality they require, 

 and they find that what they look for goes along with certain 

 properties easily tested ; they seek by rule of thumb for the presence 

 of a third, fifth, and octave in each bell, and they tap the bell in 

 certain places, as I have elsewhere described, in order to develop this 

 third, fifth, and octave ; and any ear trained in bell sounds will be 

 able to detect the presence of at least the third or fifth, and generally 

 the octave, in a good Belgian bell. The presence of these j^reponde- 

 rating and selected notes is important, as constituting the bell in tune 

 with itself, a quality of the last importance in musical suites of bells 

 tuned for the carillon. 



If, now, I am further asked upon what depends the manufacture of 

 bells possessing these properties, I must again reply generally, in the 

 first place, quantity and character of the metals ; secondly, shape, pro- 

 portion, and various thicknesses of the bell. Only two metals are now 

 used in large bells, tin and copper. The Belgians use 23 to 30 per cent, 

 of tin ; the English lean to more tin, 25 to 31 per cent. Tin makes 

 the bell sound bright, but it also makes the bell brittle ; and the reason 

 why the English can afford to put in more of this brittle element is 

 because they make their bells thicker as a rule ; and the reason why 

 they are made thicker is, that instead of being merelj chimed, they 

 are swung round on a wheel, which brings the hammer with great 

 force upon the bell. If we treated the delicate Belgian bells in this 

 rough fashion we should probably crack them, though if it were 

 known that they would be swung, the Belgian makers could doubtless 



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