SCIENCE IN THE INDUSTRIAL WORLD 



"While engaged in these experiments I was struck 

 with the remarkable disproportion in weight between 

 the membrane and the bones that were vibrated by it. 

 It occurred to me that if a membrane as thin as tissue- 

 paper could control the vibration of bones that were, 

 compared to it, of immense size and weight, why should 

 not a larger and thicker membrane be able to vibrate a 

 piece of iron in front of an electromagnet, in which 

 case the complication of steel rods, shown in my first 

 form of telephone, could be done away with, and a 

 simple piece of iron attached to a membrane be placed 

 at either end of the telegraphic circuit. 



"The results, however, were unsatisfactory and dis- 

 couraging. My friend, Mr. Thomas A. Watson, who 

 assisted me in the first experiment, declared that he 

 heard a faint sound proceed from the telephone at his 

 end of the circuit, but I was unable to verify his asser- 

 tion. After many experiments attended by the same 

 only partially successful results, I determined to reduce 

 the size and weight of the spring as much as possible. 

 For this purpose I glued a piece of clock-spring, about 

 the size and shape of my thumb-nail, firmly to the centre 

 of the diaphragm, and had a similar instrument at the 

 other end; we were then enabled to obtain distinctly 

 audible effects. 



"I remember an experiment made with this telephone, 

 which at the time gave me great satisfaction and de- 

 light. One of the telephones was placed in my lecture 

 room at the Boston University, and the other in the 

 basement of the adjoining building. One of my 

 students repaired to the distant telephone to observe the 



