THE RHONDDA COLLIERY. 



203 



great strain. The Goodman machine has its armature ar- 

 ranged horizontally, and in consequence does not heat like the 

 Sullivan. Both tlie Goodman machines cut in 7ft. deep, but 

 one only cuts 3ft. 9in. wide, while the other cuts 4ft. 



The present electric installation consists of a dynamo 

 built by the General Electric Company, which is compound 

 wound, and has four poles. It generates 220amp. at 250 volts, 

 and is belt driven from a horizontal Fleming engine. This 

 plant will shortly be substituted by a high tension plant. The 

 dynamo, which was built by Ernest Scott and Mountain, of 

 Newcastle-on-Tyne will generate 75kw. at 2200 volts. Direct- 

 driven motor transformers will be installed in the pit to re- 

 duce the voltage to 250, and there will be three branch cables 

 for the three districts. 



Fig. 169. Mouth of Intake Heading, Rhondda. 



The new high-tension cable about to be laid will be sus- 

 pended from the roof. It is a three-core, lead-covered and 

 armoured, suitable for a normal pressure of 2200 volts. The 

 soft copper wire conductors are laid up in clover leaf pattern. 

 Each core is insulated with the best Manila paper, and the 

 interstices between the cores filled with spun jute, and the 

 whole covered witli Manila paper. The paper and jute are 

 both thoroughly impregnated with resin oil. The cable is then 

 covered with a continuous sheath of pure lead, on which is a 

 layer of jute impregnated with preservative compound. This 

 is protected by two layers of galvanised steel wire, laid in 



