PUBLIC ADDRESS SYSTEM AND LONG LINES 159 



The projectors 35 and 36 covered the top of the colonnade on the 

 east side. 



Fig. 11 shows also the location of the three transmitters used dur- 

 ing the ceremonies, a, on the platform for the speakers, b, in front of 

 one of the boxes in which were placed the singers and behind which 

 was located the band, and c, at the grave. When the transmitter at 

 the grave was tested it was found that serious interference was ob- 

 tained between the speaker's voice and the sound from the projectors 

 16 to 10 inclusive. For the ceremonies at the grave, therefore, these 

 loud speakers were disconnected and those numbered 22 to 26 used 

 instead. Also in order to properly cover the inside of the amphi- 

 theatre during the ceremonies at the grave, the small projectors 30 

 and 33 were used. These were located on the arch over the platform 

 and were directed at the front seats in the amphitheatre. 



The projectors were divided up into a number of small groups and 

 so connected that the volume of sound delivered by each group could 

 be varied without affecting the other groups. This was necessary in 

 arriving at the power to be delivered by each projector to give uni- 

 form distribution and to avoid interference between different groups. 



By means of these arrangements all parts of the ceremonies were 

 carried to all parts of the audience at the National Cemetery and were 

 also delivered by means of the lines to the audiences in the distant 

 cities. 



At New York, a group of fifteen loud speakers was used in Madison 

 Square Garden to satisfactorily reach all parts of the audience and a 

 group of twenty-one loud speakers was suspended outside the build- 

 ing for the outside audience. At San Francisco, ten loud speakers 

 were used in the Civic Auditorium and seven outside. 



Use of Public Address System Apparatus with Radio 



When radio broadcasting came into general use, the apparatus 

 and methods which had been developed for the public address sys- 

 tem were applied to this new field as it also demands high quality 

 reproduction for speech and music. The transmitters and amplifiers 

 associated with them in the public address system are used in radio 

 broadcasting studios for delivering speech frequency electrical power 

 to the radio transmitter. Loud speaking receivers and amplifiers 

 lor delivering sufficient power to operate them are used with many 

 oi the radio receiving sets. 



The methods which have been employed to connect public address 

 system transmitters with toll lines are being used for the broadcast- 

 ing by radio of speeches and music given at points remote from the 



