TIN MININa IN PERAK. 87 



in length, leading into the Bidor river. It is about two feet 

 ■wide, and has staked sides and an earthen bottom. The water 

 not employed in the jet, and that used for washing purposes, 

 is led by a ditch under the end of the sluice boxes into the 

 top of the tail-race, so as to keep it clear of silt. 



There are several bends in the course of the line of sluice 

 boxes, and many small drops of six to ten inches, besides the two 

 large ones already mentioned. The boxes are mostly ten feet 

 long, constructed of two -inch meranti planks. The total length, 

 exclusive of the face ditch, is four hundred and sixty -five feet. 



The method of working is as follows. The jet of water 

 breaks down the bank of tin bearing earth, and washes it down 

 into the face ditch, from thence it enters the sluice boxes. Two 

 men are employed in the face ditch to help along the heavier 

 portions of the gravel with " changkols." Once in the sluice it goes 

 by itself till it comes to the " grizzley," where a little attention 

 is required to clear the bars from time to time of wood, roots, 

 etc., which are apt to choke it up. Then in the first set of 

 wash boxes there are some men employed with long -handled 

 "changkols," pulling the stuff upwards against the stream. In 

 fact they work just in the same way as in a " long tom," or as 

 it is called locally a " lanchut." These boxes are furnished with 

 a three or four inch high stop at the lower end of each, so 

 that there is always a certain amount of gravel and sand in 

 them, and the object of stirring this up with the " changkols " is 

 to allow the water to wash away the lighter portions of it and 

 form a concentrate rich in tin -sand. This concentrate is lifted 

 from the boxes three times a day, that is every eight hours, 

 for which purpose clean water is sent through the sluice for 

 a short time previously to clear it of mud. The concentrate 

 is then put, a little at a time, into an ordinary "lanchut" or 

 "long tom," and washed until it is clean enough to be sent to 

 the store as tin -sand. 



In the riffle boxes there are one or two men with iron rakes 

 to prevent stones from clogging them up. When they are in 

 proper working order the water goes in regular waves over 

 each, and down into the cavity formed between them, where a 

 good deal of tin is caught. These boxes are cleaned out every 

 ten or twelve days, according to circumstances, and the con- 

 centrate washed in the same way as that from the wash boxes. 



At the lower wash boxes the same procedure is followed 

 as in the first set. The tin -sand caught here is mostly fine- 

 grained, as might be expected. Any tin which escapes the riffles 

 and wash boxes settles in the tail-race, and this will be cleaned 



