304 



COALFIELDS AND COLLIERIES OF AUSTRALIA. 



Every month the trailing cable is tested by passing it 

 through a shallow bath of water from one reel to another. An 

 electric main carrying 500 volts is connected with one end of 

 the trailing cable through a special high pressure voltmeter. 

 The other main is connected with an iron plate, and dropped 

 into the water tank; by this means a defective place may be 

 localised in the section being tested. If one exists, it is then 

 repaired and again tested. After tlie whole cable has been 

 treated in this manner, it is coiled up and placed in a large 

 metal-lined water tank for six hours, and then tested by con- 

 necting one end kept out of the water to the main cable, and 





Fig. 228. Ambulance Waggon. 



the other end to the metal lining of the tank, and using an 

 ohm-meter. This must show a resistance of at least one 

 megohm. 



All about the surface works, as well as below, at suitable 

 distances apart, stand water pipes are arranged in case of fire. 



At the pit top there is the usual creeper chain, two rota- 

 ting side tipplers for the coal, and an end tippler for the dirt 

 box. The shaking screen has oblong-shaped holes cut in steel 

 plates, and a shoot at the end provided with a gate. Scraper 



