TlIK i:],A(_ K WAllLi: lNI)i;STm'. 



297 



supply is too heavy, the trees hccoiiic liclK-n-clad to an undesirable 

 extent, and otherwise suffer, ihouj^h this seldom happens. It is 

 on account of its absorptive powers tliat the black wattle can, like 

 blue s^uni ( /inc. (/lobiilits ) be used for drying up swamps, and 

 although it requires more care than blue gum at the start, it is 

 quite as effective in its action afterwards ; indeed, so aljsorptive 

 is it and so wide-spreading its roots, that few trees survive inter- 

 mixed with black wattle, except the rainfall is heavy, or the soil 

 very deep."' 



This has been misconstrued by some, and 1 now wish io make 

 clear that the drying out referred to above is entirely local ; that 

 the black wattle is pumping its 40 inches of water into the atmo- 

 sphere so long as it can find it, and that conse([uently the sur- 

 rounding atmosphere becomes more moist, though the underlying 

 soil may become depleted of water to the extent of drying out 

 streams or spriiigs served by that area. In proof_of this I submit 

 the following table showing the rainfall at Maritzburg during 20 

 >ears (all there is on record) as supplied by the Chief Meteor- 

 ologist, Pretoria, on March 22, 191 5 — the first ten years being 

 before wattles were abundant round Maritzlnu-g, the second ten 

 years, since they became so. 



339.64 



1226 



Average 10 years 33-964 inches on 

 122.6 days. 



358.98 1183 



verage 9 years 39.88 inches on 

 131.4 days 



The fact that the average rainfall has Ijeen six inches higher 

 during the past ten years than during the previous ten years may, 

 of course, be open to cyclic or other explanation quite apart from 

 wattles, and may be found to correspond with similar increase 

 elsewhere where wattles can have no effect, but till one or both of 

 these proi)ositions are proved it is fair to accept the greater 

 general humidity caused by the tran.spiration of wattles as at least 

 a contributory cause. 



No pai)er on wattles c(juld be complete witliout reference to 

 the wattle pests. 



But as Mr. Hardenberg is to contribute a paper on these, 1 

 will omit practically all of what I would otherwise have said. 



(}overnment's action in investigating these pests is highly 



