26 Report S.A.A. Advanxement of Science. 



of the observer, and the precision of his tools and methods. A 

 determination is only exact — its result only a true fact — when all the 

 possible sources of error which can possibly affect it, have been 

 carefully computed and estimated, and the uncertainty of the result, 

 as well as the result itself, are stated. The value of a result, as a 

 published addition to Science, will very much depend on the clearness 

 of the statement as to the precautions which have been taken for 

 elimination of systematic errors and the completeness of the deduc- 

 tion of its probable or its possible error due to sources of all kinds — 

 systematic and accidental. 



We may safely state that it is largely to the increased attention 

 paid to this necessary feature in the conduct and publication of re- 

 searches that we owe much of the scientific advance of the past 25 

 years. 



Were this a purely Physical, Chemical, Astronomical or Geo- 

 detic Association, one would be tempted to dwell on this subject for 

 the remainder of the Address, and to illustrate by examples the 

 fuller significance of these remarks ; but as there are many other sub- 

 jects w^hich it seems desirable to touch, it must suffice to quote Lord 

 Kelvin's words of over 30 years ago, viz. : 



" Accurate and minute measurement seems to the non- 

 scientific imagination a less lofty and dignified work than look- 

 ing for something new. But nearly all the grandest discoveries 

 of science have been the rewards of accurate measurement and 

 patient, long-continued labour in the minute sifting of numerical 

 results.'' 



That is undoubtedly true of Astronomy, Chemistry and Physics- 

 - — 1 believe it to be increasingly true of Geology and Physiology, and 

 probably also of other sciences. 



Turning now from the duties of the Scientist to Science, let us 

 consider briefly the duties of our Association to Scientists and to 

 other Scientific bodies. 



The ol)jects of our Association are defined by our Constitution 

 as follows.: 



" To give a stronger impulse and a more systematic direc 



tion to Scientific enquiry; to promote the intercourse of Societies 



and Individuals interested in Science in different parts of South 



Africa ; to obtain a more general attention to the objects of 



pure and applied Science, and the removal of any disadvantages 



of a public kind which may impede its progress." 



This definition is, as nearly as possible, identical with that 



adopted by the British Association, and it has proved to be a sound 



and satisfactory basis for the work carried on by that body with so 



much success for more than 70 years. 



You will observe that we use the words to promote " the inter 

 course of Societies and individuals interested in Science," instead 

 of " the intercourse of those who cultivate Science," and this altera- 

 tion was advisedly introduced on two accounts. 



In the first place we think it the more accurate description of 

 our own possibilities, and. if I may venture to sav so, it is also a 



