CANADA PORCUPINE 



69 



unit of error on the returns. These results have been separately 

 tabulated and have also been combined with the time data as 

 iVIiss Hicks recommends. These results are shown in the last 

 two columns of figures in table XIII. Repeated efforts have 

 been made to superpose these latter curves upon the time and 



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Hatz Ji. 



error curves in plate II, but it has been found impracticable. 

 Consequently, a curve based upon Miss Hicks' recommenda- 

 tions for counting errors (curve M) and also a curve which 

 combines the revised error and time data (curve N) are shown 

 in plate III. The writer is unable to determine wherein the 



