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ANNUAL REPORT SMITHSONIAN INSTITUTION, 1935 



actual rainfall with that given by the formula is shown in figure 

 10. Similarly, the 0.56 of South Africa becomes 0.72. But a cer- 

 tain amount of the improvement effected in this way by selecting 

 the biggest factors is bound to be fictitious, even when there appear 

 to be adequate independent reasons for thinking that the relation- 

 ships are real; and, if this precaution is ignored, the more promis- 

 ing the formula, as indicated by the closeness of its apparent rela- 

 tionship, the greater is the likelihood of disappointment. 



It must be admitted that a real control of 0.7 by previous condi- 

 tions is about as good as is now available for forecasting, and the 

 difference between the actual and the forecasted amounts will still 

 be considerable; so predictions can only be issued with restraint if 

 public confidence is to be won. The natural consequence is silence, 

 except when the indications are markedly favorable or unfavorable : 

 In a race with 30 starters a conspicuously good horse may, without 



FiGDBB 10. — Northeast Australian rainfall, October to April. 



undue risk, be backed to come in within the foremost 6, and we may 

 feel confident that a thoroughly bad animal will be in the last 6; 

 but it would be unwise to hazard much on the likelihood that a com- 

 monplace individual will finish among the central 6. It may at 

 first sight seem a confession of weakness to issue no forecast when 

 conditions appear roughly normal; but it is better to admit your 

 limitations, and only speak when you can do so with some safety, 

 than to issue predictions when they are little more than guesses. 



The objection is sometimes raised that though a foreshadowing 

 of abundant or scanty rain over a region may be right four times out 

 of five, owing to local variations the predictions will not be so suc- 

 cessful when applied to a particular farm ; and it must be admitted 

 that this criticism is valid. But in England, as I learn from Sir John 

 Russell, there are modifications of treatment and manuring that are 

 appropriate before wet seasons and others before dry; in South 

 Africa, in hilly country, the upper levels are better for cultivation in 



