202 THE RUBBER TREE BOOK 



of the mills. This shafting is usually run at a speed of 75 to 100 

 revolutions per minute. The Ceylon style does not appear so 

 suitable. The use of belts always means a loss of power gener- 

 ally estimated at from 10 to 15 per cent. Now, if a planter 

 has an engine of, say, 50 horse-power, and is losing from 5 

 to 7^ horse-power every working day, it is easy to estimate 

 the annual loss involved. By the other method of drive the 

 loss of power is minimized. The risk of accidents to coolies 

 and others attending the mills is also lessened. 



Planters should always specify the back-driven type of mills, 

 as in these the drive is kept clear of much of the dirt and water 

 showered down on centre-driven mills. 



There is a tendency to increase the diameters of the rollers 

 on mills. Formerly 9" x 18" was the standard in the Federated 

 Malay States, but recently orders have been received by 

 engineers for mills with rollers 14" x 24" in diameter. Such large 

 mills indubitably take more power to drive them, but they do 

 more work and the rollers last much longer no small advantage. 



The water used for purposes of washing and manufacturing 

 rubber should be pure, otherwise first-grade rubber cannot be 

 turned out. Many managers seem very indifferent about this 

 matter, and are content to use well or river water without any 

 attempt to purify it. Wet sheets of rubber should never be 

 carried out into the sunlight from the factory to the drying- 

 house. A properly-covered-in, not merely roofed, passage 

 should always be erected. If the drying-room is situated above 

 the factory, of course this instruction is not necessary. 



