io THE POPULAR SCIENCE MONTHLY. 



the principal valuable positive conclusions have been derived from lin- 

 guistic researches. In the dispute as to the relative merits of the 

 zoological and philological methods in ethnology, I accordingly side 

 with the advocates of the latter ; and, in regard to the special subject 

 of this paper, I say with Quatref ages, in the words of Virgil, " Ne cre- 

 de colori." 



+** 



THE CARBON BUTTON.* 



By E. A. ENGLEK, A. M. 



ALTHOUGH the telephone seems to have sprung up among us 

 very suddenly, there have been steps in its development which 

 show that the difficulties encountered in devising a means for the 

 transmission of articulate speech have not been overcome altogether 

 by a single stroke of individual genius, but singly by the patient and, 

 for the most part, unrewarded labor of many. Each stage of its devel- 

 opment was the outgrowth of suggestions obtained from previous ex- 

 periments. Of the instruments which served their purpose in the dis- 

 covery of the properties of the carbon button, a brief description will 

 be given in this paper. 



Sound is known to be produced by vibrations, generally of air ; 

 differences between sounds are due to differences in vibration. There 

 are but three essential characteristics to be noted, all dependent upon 

 the vibrations of the air : 1. The pitch, by virtue of which a sound is 

 called high or low, and which depends upon the number or rapidity of 

 the vibrations ; 2. The intensity or loudness, which is determined by 

 the amplitude of the vibration ; 3. The quality by which we distin- 

 guish the corresponding tones of different instruments, and which 

 depends on the form of the vibration. In order to obtain an exact 

 reproduction of any sound, its pitch, intensity, and quality must be 

 exactly reproduced ; and, to render this possible, the rapidity, ampli- 

 tude, and form of the vibration must be exactly reproduced. 



For producing sound at a distant place two methods suggest them- 

 selves : 1. Actually to transmit the sound vibrations through the air ; 

 this is the method employed in the speaking tube. 2. To reproduce 

 the sound vibrations at the distant station ; this is the method em- 

 ployed in the telephone. The previous development of the telegraph 

 naturally suggested electricity as the agent to carry the vibrations 

 from one place to another. It thus became necessary to convert 

 sound waves into electric waves and vice versa, and experiments look- 



* This paper, at first intended for a special occasion, has been published at the sug- 

 gestion of several friends. In its preparation, use has been made of information to be 

 found in George B. Prescott's work on the telephone, and in the journals of science. 

 Most of the illustrations are from Prescott's work. 



