DEVELOPMENT OF THE TELEPHONE 



straight line or direct, but in one bended in many 

 angles." 



Just what Hooke's method of telephoning may have 

 been does not appear. Presumably it was some such 

 arrangement as the string-diaphragm "speaking tele- 

 phone" to be referred to in a moment. But in any 

 event nothing of practical importance ever came 

 of it. 



A step toward the development of a practical tele- 

 phone was taken in 1819 by Sir Charles Wheatstone who 

 invented what is known as the "magic lyre telephone," 

 by which musical notes were made to respond to similar 

 tones at some distances. But it was not until several 

 years after the invention of the telegraph that any serious 

 attempts were made to perfect the speaking telephone. 

 About 1867, however, a great number of instruments 

 known as "membrane telephones" were put upon the 

 market as toys. This form of telephone, familiar to every 

 schoolboy in his studies of physics, consists of two 

 cups, the bottoms of which are made of a tightly 

 stretched membrane, or parchment, perforated in the 

 middle by a string fastened with a knot at the end, and 

 connecting the two cups. With such an arrangement a 

 person speaking into one of these cups as into the 

 transmitter of a telephone may convey messages a con- 

 siderable distance to a person holding the other cup 

 to the ear, the string meanwhile being drawn taut. 

 Verbal messages have been sent and received in this way 

 at distances ranging from 1 50 to 1 70 yards, but these could 

 only be sent when the string was continuous and not 

 resting against any intervening object. They could not, 



