SEVENTY-FIVE YEARS OF THE TELEPHONE 219 



patent application on granules of carbonized hard coal was filed in 1886/'^'^ 



As early as 1878, the idea of mounting both the transmitter and the re- 

 ceiver on a common handle had been invented and such "handsets" were 

 used by boy operators in the 'Gold and Stock' telephone exchange in New 

 York City .3 



In 1878, Watson patented his polarized two-gong ringer and designed 

 the hand-cranked magneto for its actuation. The receiver-operated switch- 

 hook was invented in 1877. Patent applications were filed in 1877 covering 

 the association of an induction coil with the transmitter. 



Thus, by the end of 1878, the general nature and principles of operation 

 of most of the components of the present-day telephone set had been in- 

 vented. One of them, the ringer, has come through the years in a form very 

 similar to its original design. Other components, such as the carbon trans- 

 mitter and the handset, have called for a large amount of research and de- 

 velopment to make the appHcation of the general principles satisfactory for 

 the conditions of modern commercial telephony. 



Other important inventions which affected the telephone set were the 

 centralized battery for signahng in 1880 and the common battery for both 

 talking and signaling purposes in the latter part of that decade. The bi- 

 polar hand receiver came into use in 1890 and the White solid-back carbon 

 transmitter was invented in 1890. The rotary dial was first used by the 

 Automatic Electric Company in 1896. 



Figure 2 shows telephone equipment manufactured in 1882 by Charles 

 Williams, Jr., in whose shop Bell had met Watson. This represents an early 

 idea of combining in a unit-mounting the various pieces of apparatus for 

 the use of the telephone. This unit — suitable for installation on the premises 

 of a telephone subscriber — may be taken as typifying the first step toward 

 the telephone station set as we know it. This 1882 telephone set included 

 the Blake transmitter, single-pole hand receiver, ringer, magneto, switch- 

 hook and induction coil. Incidentally, this arrangement of apparatus was 

 later produced by the Western Electric Company which became the manu- 

 facturing organization of the Bell System in 1882. 



Many changes have taken place in the elements and form of the station 

 sets used in the Bell System since this 1882 set. Certain outstanding steps 

 are illustrated in Fig. 3, showing a deskstand of 1919, the handset of 1927, 

 the combined set of 1937, and the set on which production started in 1950. 

 The 1919 set used a solid-back transmitter and a bipolar hand receiver 

 which were the results of several stages of improvement of the types intro- 

 duced in the 1890's. The 1927 handset required the invention of important 

 changes in the granular carbon transmitter. The 1937 set introduced a new 



« Ibid., Chap. V. 



^> Numbers refer to items in the Bibliography. 



