MECHANICS AND USEFUL ARTS. 71 



dies or pieces of machinery ; it is unnecessary to soften it over a fire, as 

 when hardened in water. 



ON BELLS AND BELL-FOUNDING. 



The following memoranda on bells and bell-founding, is derived from a 

 paper on the above subject read before the Royal Institution of Great Brit- 

 ain, by Mr. Denison, the founder of the bells intended for the clock and 

 peal of the palace of Westminster, London. 



The problem we were called upon to solve in making the largest bell, 

 said Mr. D., was, not to produce a bell of any given note, but to make the 

 best bell that can be made of a given weight of fourteen tons, which had 

 been fixed as the intended weight. When I say the best bell that can be 

 made, I mean a combination of the most powerful and most pleasing sound 

 that can be got not, observe, the deepest sound; for we could get any 

 depth of note we liked out of the given weight, by merely making the bell 

 thinner, larger, and worse, as I shall explain further presently. All that I 

 have to do, therefore, is to describe the ooservations and experiments which 

 led me to adopt the particular form and composition which have been used 

 for this the largest bell that has ever been cast in England. The result is, 

 undoubtedly, a bell which gives a sound of a different quality and strength 

 from any of the other great bells in England. Of course it is very easy to 

 say, as some persons have said, that we have got a clapper so much larger 

 than usual, in proportion to the bell, that the sound must needs be different. 

 But the reply to that is equally easy ; the bell-founders always make the 

 clapper at their own discretion ; and in order to make the most they can of 

 their bells, you may be sure they will make the clapper either as large as 

 they dare, with regard to the strength of the bell, or as large as they find it 

 of any use to make it ; because there is always a limit, beyond which you 

 can get no more sound from a bell by increasing the clapper. In the West- 

 minster bell we found that we could go on increasing the sound by increas- 

 ing the clapper up to thirteen cwt., or say twelve cwt., excluding the 

 shank or handle of the clapper, or about one twenty-seventh of the weight 

 of the bell ; which is somewhat higher than the proportion found to hold 

 in some of the great continental bells ; but two or three times as high as the 

 usual English proportion. 



I have said already that you may get any depth of note out of a bell of 

 any weight by making it thin enough. At first, everybody who hears a 

 bell, like that which stood at the west end of the Exhibition of 1851, sound- 

 ing with twenty-nine cwt. very nearly the same note as our sixteen-ton bell, 

 is ready to pronounce the common form of bell, with a sound-bow of one 

 twelfth or sixteenth of its diameter, a very absurd waste of metal. But 

 did it ever occur to them to consider how far they could hear that twenty- 

 nine cwt. hemispherical bell ? It could not be heard as far as a common 

 bell of two or three cwt. ; and before you get to any great distance from a bell 

 of that kind, the sound becomes thin and poor, and what we call in bell- 

 founding language, potty. Up to seven or eight inches, these bells do 

 very well for house clocks, to be heard at a little distance ; but nothing, 



