70 Beport of the Bilharzia Mission in Egyjjt, 1915 



with weeds, which frequently afford sufficient protection to the 

 molluscs to enable them to survive for a considerable period. 

 In Egypt, drainage is always effected by means of open drains. 

 The periodical clearing of these drains must, therefore, be regarded 

 as an essential part of any scheme for the eradication of bilharziosis 

 until the open drain can be abolished. 



The English system of field drainage by underground pipes has 

 scarcely received proper trial in Egypt. Quite recently the State 

 Domains Administration made some experiments on the washing 

 of salted land by filtration into drain pipes and this method was 

 found to be better than that of filtration into open drains. The 

 cost, however, proved out of proportion to the extra benefit from 

 the agriculturists' point of view. 



Although the initial cost may seem considerable, it should not 

 be overlooked that there would be a distinct saving in other 

 directions. The annual charges for clearing the open drains 

 would be abolished, there would be no heavy losses or damage 

 through the falling of live stock into the drains, and the land 

 recovered would represent a considerable increment of capital. 



Lang-Anderson has estimated that if pipes could be obtained 

 in Egypt at about the same cost as prevails in England, the 

 conversion of an open drain 300 metres in length into a covered 

 drain would involve an outlay of a httle over £3. About 1,200 

 square metres of land previously occupied by the open drain would 

 then be available for agricultural purposes. Valued at <£42 per 

 feddan, this recovered land would be worth £12. 



The mole drain plough is said to be an efficient and very cheap 

 method of drainage. Lang-Anderson believes that the soil of 

 Egypt would give a satisfactory bore to this machine. If this 

 proved to be the case earthenware pipes could be dispensed with. 



The canals are closed annually for a period of a 



Cleakances ^^O'^^^' usually from December 25 to January 25, to 



allow of the removal of silt. If it were practicable 



to carry out these canal clearances at the commencement of the 



summer in conjunction with the rotations of water, the work 



should greatly assist in the elimination of the fresh-water molluscs. 



As the anti-bilharziosis measures proposed 



Campaign depend for their success upon the summer rota- 

 ions, the campaign would be confined to the 

 months from April to August. We now proceed to acquaint our- 

 selves with the agricultural activities in perennially irrigated land 

 during these months, to see to what extent these would assist or 



