THE UNIVERSAL FAMILY PAPER FOR INTER-COMMUNICATIONS ON 



Conducted by WILLIAM KIDD, of Hammersmith,— 



Author op the Familiar and Popular Essays on "Natural History;" "British Song 

 Birds;" " Birds of Passage ; " "Instinct and Reason;" " The Aviary," &c. 



"the OBJECT op our work is to make men WISER, without obliging them to turn over folios and 

 auARios. — to furnish matter for THINKING as well as READING." — Evelyn. 



No. 42.— 1852. 



SATURDAY, OCTOBER 1G. 



Price M. 



Or, in Monthly Parts, Price Is. Id. 



THE NATURE OF SOUND:— No. II. 



(Continued from page 146 .) 



Many" experiments have been made on 

 the capability of water to transmit sound. 

 The Abbe Nollet among others, took much 

 pains to decide the question. By practice he 

 acquired such management of himself under 

 water, that he could hear the sound of the 

 human voice, and even recognise airs of 

 music. When he struck together two stones 

 which he held in his hands, his ears were 

 shocked almost beyond bearing ; and he even 

 felt a sensation on all the surface of his body, 

 like that produced when a piece of metal held 

 in the teeth is struck by another piece of 

 metal. He observed also, that the more 

 sonorous bodies, when struck under water, 

 gave a less vivid impression than others less 

 sonorous. These experiments were success- 

 fully repeated by the late Dr. Monro, of 

 Edinburgh. 



All bodies are not equally fitted for pro- 

 ducing sound. Those which have the 

 greatest degree of elasticity, appear to be the 

 most sonorous. It is owing, indeed, to the 

 great expansible force and elasticity of the 

 air, that gunpowder and the electric flash, 

 by rending it, and forming a vacuum, occa- 

 sion the loud sounds which often strike us 

 with terror. The cracking of a wagoner's 

 whip affords a good illustration of the sound 

 of thunder or any other explosion. The 

 sudden jerk of the end of the whipcord dis- 

 places a portion of air, and forms an empty 

 space into which the adjacent air violently 

 rushes. The air which formed the several 

 sides of this empty space, thus collapsing 

 with a shock, produces the sound. 



The changes which take place among the 

 minute particles of bodies, in consequence of 

 the vibrations from which sounds arise, are 

 remarkably different in metals, in wood, and 

 in musical strings. This can be illustrated 

 in the case of metals, by repeating the expe- 

 riments of Dr. Chladni, of Berlin, who took 



plates of different metals, and having strewed 

 them with fine sand, caused them to sound 

 by drawing over their edge the bow of a 

 violin. In these experiments, the sand is 

 found to arrange itself according to the vibra- 

 tions produced, and it is curious that the 

 form which the sound takes is different in 

 different metals. Anybody can easily repeat 

 those experiments — with sheet lead, sheet 

 iron, copper plates, &c. 



In the case of musical strings, as in other 

 sounding bodies, the quicker they vibrate the 

 more sharp is the sound ; and this does not 

 depend at all on the slowness or quickness 

 with which you strike them, but on the ten- 

 sion and thickness of the string. We are 

 told, but on the authority of what experi- 

 mental calculation we know not, that the 

 gravest sound which the ear can perceive is 

 formed of two thousand vibrations in a 

 second ; and the sharpest sound, of twelve 

 thousand. 



In the pianoforte and the harp, the high 

 treble notes are produced by short, small, 

 tight strings ; and the deep low bass notes by 

 strings which are long, thick, and little 

 stretched. 



On striking a bell, or a musical string once, 

 we may hear by minute attention, first the 

 fundamental sound or note ; secondly, the 

 octave, or eighth note above ; thirdly, the 

 twelfth ; and, lastly, the seventeenth. These 

 are called harmonic notes. 



It is from the vibrations of several strings 

 taking place in a certain order, that agree- 

 able, or disagreeable feelings are excited. The 

 sounds producing these opposite feelings, are 

 said to be harmonious or to be discordant. 

 For example, if the vibrations of two strings 

 are performed in equal times, the same tone 

 is produced by both, and they are said to be 

 in unison. Again, if one string vibrate in 

 half the time of another, the first vibration 

 of the latter will strike upon the ear at the 

 very same instant as the second vibration of 

 the former. 



These will accordingly agree or harmonise; 



Vol. II. 



