170 EGYPTIAN AGRICULTURE. 



per dip, and a man could dip about 6 times per minute, 

 lifting 7 metres per hour if working continuously. Arm 

 work is fatiguing, as much effort being needed to force the 

 trough into the water as to raise it after it has left the 

 surface. By making a trap door in the bottom of the 

 opening upwards and hinged with a piece of leather the 

 effort of forcing down the trough into the water to over- 

 come the resistance of displacement is saved. 



A man lifting weight with his arms can only exert 

 20 kilog. effort but using the weight of his body his effort 

 is 60 kilog. The writer made a pair of troughs with posts 

 and cross-bar to give secure support to a man who by 

 treading alternately on each trough exerted the whole weight 

 of his body. The troughs were made larger, were fitted with 

 traps, and with counterpoises to raise and discharge them. 

 The native Egyptian is relatively much stronger in his 

 legs than in his arms 'and his average weight is quite 

 60 kilograms. He could go on a much longer time 

 working this water treadmill and lifting very much more 

 water than he could when standing in water up to his 

 middle and working with his arms. The apparatus, 

 however, is only good for a lift of 25 to 50 centimetres. 



Nattala. Is the simplest of all water lifts, being nothing 

 more than a straw mat basket, closely plaited, with four 

 cords attached. Two men standing well above the surface 

 of the water and opposite to each other take a pair of 

 cords each, swing the basket out over the water, and on 

 the return swing dip it down, and scoop up a fill of water 

 which they discharge over a little bank into the irrigating 



