414 Mr. F. Galton. [May 27, 



Table VI. — Example of one Calculation in each of the 3 Cases. 



Ancestry and their 

 eye- colours. 



I. 



II. 



III. 



No. about whom 

 data exist. 



Contribute 

 to 



No. about whom 

 data exist. 



Contribute 

 to 



No. about whom 

 data exist. 



Contribute 

 to 



Light. 



Dark. 



Light. 



Dark. 



JUiglll . 



uarK. 



Light-eyed parents . . 



Light - eyed grand- 

 Hazel - eyed grand- 

 Dark - eyed grand- 



2 



0'60 

 0-28 



12 



1 



2 

 1 



0-16 

 0-20 



25 



0-12 

 0-16 



Oil 



1 

 1 



1 



2 

 1 



0-16 



0-08 

 10 



0-12 



0-09 

 0-25 



0-06 

 0-08 



0-06 



Residue, rateably as- 









Total contributions . . 





0-88 



12 



61 



0-39 



0-46 



54 







1-00 





1-00 





100 



The pair of columns headed I in Table VI shows the way of sum- 

 ming the chances that are given in the columns with a similar heading 

 in Table V. On the method there shown I calculated all the entries 

 that appear in the columns with the heading I in Tables III and IV. 



IT. Eye-colours given of the four grandparents — 



Suppose r to be possessed by G x and that nothing whatever is 

 known with certainty of any other ancestor of M. Then it has been 

 shown that the child of (that is P) will possess ; that each of 

 the two parents of G 1 (who stand in the relation of Gr 2 to M) will 

 also possess ±r ; that each of the four grandparents of G 1 (who stand 

 in the relation of G 3 to M) will possess -§-r, and so on. Also it has 

 been shown that the shares of their several peculiarities that will on 

 the average be transmitted by P, Gr l9 G 2 , &c, are -^l., &c., 



respectively. Hence the aggregate of the probable heritages from G l 

 are expressed by the following series : — 



r {l x w +ix & + l x2x i + l x * 4s+ &c -} 



