26 THE ERRORS OF PRECISION. 



Our Little Diagram Shows the Facts. 



But the range of the individual determinations in the 

 seven series necessarily show still greater divergencies than 

 the mean values of these series. In order to present these 

 variations to the eye as they really are so as to obtain a 

 proper conception of the magnitude of these variations, I 

 here reprint the diagram from page 193 of my True Atomic 

 Weights published in 1894. See Plate I. 



In this diagram the actual values given by Professor Mal- 

 let himself are entered as dots representing also the amount 

 of gold used in the particular determination. 



The scale is marked on the horizontal line for the gold 

 used (in grammes), and on the vertical line for the atomic 

 -weight found. The dots representing the actual determina- 

 tions of any one series are marked in the same manner, and 

 connected by a line. 



The mean value of each series is also entered by a dot 

 surrounded by a circle, and marked by the roman numeral 

 of that series. In this way the diagram here given repre- 

 sents graphically and according to scale all the most essen- 

 tial results of the chemical work of Professor Mallet, as 

 given by himself. 



It is seen, that neither the individual determinations, nor 

 the mean values of the series, show any tendency to cluster 

 near any particular point. 



Mallet did not Hit the Mark. 



If the field represented in our diagram were considered 

 as a target and Professor Mallet were to use seven different 

 rifles to hit a definite point on that target, and the marks 

 made in the target were connected by lines for each rifle, we 

 would in that diagram see the evidence that the seven rifles 

 were equally bad, and the shooting so scattering as to show 

 no center hit indicated or marked by any grouping of dots. 



In fact, the determinations made by Mallet scatter greatly 

 and cover the entire field on either side of 197 quite evenly, 

 extending fully three tenths below and as much above this 

 line. 



