BOOK XXXIII. XXI. 74-76 



tasks ; the dip of the fall must be steep, to cause 

 a rush rather than a flow of water, and consequently 

 it is brought from very high altitudes. Gorges 

 and crevasses are bridged by aqueducts carried 

 on masonry ; at other places impassable rocks 

 are hewn away and compelled to provide a position 

 for hollowed troughs of timber, The workman 

 hewing the rock hangs suspended with ropes, so that 

 spectators viewing the operations from a distance 

 seem to see not so much a swarm of strange animals 

 as a flight of birds. In the majority of cases they 

 hang suspended in this way while taking the levels 

 and marking out the Hnes for the route, and rivers 

 are led by man's agency to run where there is no 

 place for a man to pUmt his footsteps. It spoils the 

 operation of washing if the current of the stream 

 carries mud along with it : an earthy sediment of 

 this kind is called uritnn. Consequently they guide 

 the flow over flint stones and pebbles, and avoid 

 nrium. At the head of the waterfall on the brow of 

 the mountains reservoirs are excavated measuring 

 200 ft. each vray and 10 ft. deep. In these there 

 are left five sluices with apertures measuring about a 

 yard each way, in order that when the reservoir is 

 full the stopping-barriers may be struck away and 

 the torrent may burst out with such violence as to 

 sweep forward the broken rock.« There is also yet 

 another task to perform on the level ground. 

 Trenches are excavated for the water to flow through 

 — the Greek name for them means ' leads ' ; and 

 these, which descend by steps, are floored with 

 gorse * — this is a plant resembling rosemary, which 

 is rough and holds back the gold. The sides are 

 closed in with planks, and the channels are carried 



59 



