lo Feb., 1911-] 



Irrigation. 



The proper provision of head ditches cannot be too strongly empha- 

 sized ; and I am entirely with those authorities who decline to deliver water, 

 unless the means of distribution are adequate. Where it happens that a 

 head ditch can l>e constructed on a level contour little remains to be done 

 beyond providing outlets to the field. The simplest form is to out gaps 

 in the bank with a shovel and regulate the flow of w;.'e.- by n:eans of 



45. OUTLET FROM HEAD DITCH. 



clods, pieces of sacking, bunches of weeds.. &c. It is rather a slovenly 

 practice and results in unsightly holes accumulating, but it is effective and 

 certainly permissible where means are limited. The better plan is to pro- 

 vide some kind of pipe of suitable capacity and length, the latter being 

 governed by the width of the ditch bank. If circular pipes are used 

 plugs of some kind must be provided, to regulate the discharge. Prefer- 

 ably, these should be of cork; wooden plugs often swell and get jambed 

 and in the process of removing them many pipes are displaced or damaged 

 or broken. The plug should appear wedge-shaped in section as shown in 

 No. 46 and be slightly tapered, which admits of regulating discharges to 

 any volume desired within the capacity of the pipe. 



46. PLUG FOR PIPE. 



ANOTHER FORM OF PLUG. 



If the supply of water only reaches the top of the pipe the plug should 

 Ije turned sideways. Another plug is made by covering the mouth of the 

 pipe with an old jam tin which either just fits inside or outside the pipe 

 and in which a cut has been made in one side a-; shown in No. 47 ; a 

 hoop-iron handle is attached, the lugs of the handle projecting beyond the 

 I'dge of the tin to prevent it slipping into the pipe when used inside. The 

 form of the aperture allows of a very nice adjustment of flow. 



7 , 



J. 



I 



48. .SK( HON ul 

 olJTI.ET. 



49. SKC I ION 01 ( ii: 1 I.K 1 

 .Nor RKfOMMKNDKIi. 



;o. LONGITUDINAL SECTION 

 OF 01; r LET. 



PijXfs may In- either earthenwarr, iron (old water pipes), galvani/ed 

 iron (downpipc). or wood. Thr first .ind third cla.sses are not to l>e recom- 

 mended as ihey are easily damaged. The second class is practically ever- 

 lasting ; secondhand wat«'r <>r steam pipes are pnMurable in .some places 

 at cheap rates. Square wood«'n pipes are very serviceable and durable; 

 thev are easilv made and rtgulated, and are on the whole to be preferred. 

 I usf them made of red-gum. 4 inches x \\ inches, put together as shown in 

 No. 48 to give the greatest waterway. If built as .shown in No. 49 the 

 area is 20 per cent. less. The inlet is made as in No. 50, the diagonal piece 

 i»eing a shuttrr made of stift" galvani/rd iron sliding in saw cuts made in 

 the wood. th<- top or ((Acr l)oard t<Tiuinatitig at th«- shuttrr. Thesr pip.-s. 



