LEAD-COVERED PAPER-INSULATED TELEPHONE CABLE 459 



controller for regulating the temperature and one controller as a check 

 instrument and to actuate an alarm if the temperature goes above or 

 below a predetermined limit. Each instrument has its own thermo- 

 couple. 



To reduce to a minimum the possibility of a prolonged shutdown 

 due to a breakdown in the lead conveying line, a duplicate pipe system 



Fig. 27 — Antimony charging mechanism. 



is provided which can be put into service in a short time in case of 

 failure of the line in use. The line ordinarily used is the one nearest to 

 the presses and is the service line while the line one foot to the rear but 

 at the same height, is called an emergency line. 



The main-line piping system is made of seamless steel tubing sup- 

 ported on a roller-conveyor system to take care of the expansion and 

 contraction which amounts to 6| in. per 100 linear feet at 750° F. or a 

 total of approximately 20 in. under normal working conditions for the 



