Sounding bodies are of two kinds; those unelastic ones, which being struck, return but a single sound; and those more elastic returning a succession of sounds, which uniting together form a tone. This tone may be considered as a number of sounds produced one after the other by the same body, as we find in a bell, which continues to sound for some time after it is struck. A continuing tone may be also produced from a non-elastic body, by repeating the blow quick and often, as when we beat a drum, or draw a bow along the string of a fiddle. Considering the subject in this light, we shall find the number of blows or quickness of repetition will have no effect in altering the tone, but only make it more even or more distinct, whereas if we increase the force of the blow by striking the body with double the weight, this will produce a tone twice as loud as the former. From hence we may infer, that all bodies give a louder and graver tone, not in proportion to the number of times they are struck, but to the force that strikes them. And if this be so, those philosophers who make the tone of a sonorous body, a bell, or the string of an harpsichord, for instance, to depend upon the number only of its vibrations, and not the force, have mistaken what is only an effect for a cause. A bell, or an elastic string, can only be considered as a drum beaten; and the frequency of the blows can make no alteration whatsoever in the tone. The largest bells, and the longest and thickest strings, have the most forcible vibrations; and, therefore, their tones will be more loud and more grave in proportion to the size and weight of the body with which they are struck.