Ch. 6: South African Diamonds II

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	south African diamonds (Continued) The average output from each mine today is over 5,000 sixteen cubic foot truck loads during an eight hour shift, which is equal to 4,000 tons. The ground is loaded into trucks, mechanically transported to the main rock shaft and loaded into the hoisting skips. At one time electric locomotives were used for haulage purposes, but these have been discarded and an endless rope engaging with jockeys on the top of the trucks is now in use. The rope is driven by electric motors through suitable gearing. Each skip in the main shaft holds ten of these trucks, and to prevent confusion at the shaft the full trucks are attached to the haulage rope in spans of five. The full trucks as they run past the loading box are automatically tipped, ten truck loads being fed alternately into each half of the box. When a hoisting skip, after its trip to the surface, arrives at the bottom of the shaft, it comes to rest upon a strong carrying beam so placed that the upper lip of the skip is just below the door of the loading box. The door is opened by means of a machine operated by compressed air, and the ten loads which have, during the time occupied by the trip, been tipped into the box slide into the skip at once. The box door is closed and the signal is given to the engine driver at the surface for him to commence his wind. The time occupied in filling the skip is about five seconds. At first diamonds were found only on the surface. It was soon learned that diamonds were found twenty feet below the surface. After this was learned, mining started in earnest. Two farms were sold for a few thousand dollars 47

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