INSTALLATION OF FIXED EQUIPMENT 



87 



Fig. 42 Standard telephone installation 

 (a) Front view, (&) Back view, (c) Side view 



2 RENEWAL 



Regular systematic renewal -of all batteries at least once a year is necessary. In 

 some cases more frequent renewals will be required'. For such places the 3-in-l bat- 

 tery, which consists of three cells inclosed in a waterproof casing with only two 

 exposed connecting-posts, will often be found desirable as it has a. somewhat longer 

 life. Batteries deteriorate rapidly whether in use or not. 



Two new batteries should never be installed with one old battery, nor one new 

 battery with two old batteries, as one poor battery will spoil the efficiency of the good 

 ones. 



Fig. 43 Method of connecting dry batteries for a telephone 



