202 



NATURAL INHERITANCE. 



is made. For example, in Table 6, opposite to the argument l - 00, the 

 entry of '50 is found ; that entry becomes *25 in 6a, and 25 in 66. 

 In Table 7 the argument is 25, and the corresponding entry is 1"00. 

 The meaning of this is, that in 25 per cent, of the cases the greatest 

 of the Errors just attains to ± l - 0. Similarly Table 7 shows that 

 the greatest of the Errors in 30 per cent, of the cases, just attains 

 to ± l - 25 ; in 40 per cent, to l - 90, and so on. These various per- 

 centages correspond to the centesimal Grades in a Curve of Distri- 

 bution, when the Grade 0° is placed at the middle of the axis, which 

 is the point where it is cut by the Curve, and where the other 

 Grades are reckoned outwards on either hand, up to + 50° on the 

 one side, and to — 50° on the other. 



To recapitulate : — In order to obtain Table 7 from the primary 

 Table 5, we have to halve each of the entries in the body of Table 5, 

 then to multiply each of the arguments by 100, and divide it by 

 *4769. Then we expand the Table by interpolations, so as to 

 include among its entries every whole number from 1 to 99 inclusive. 

 Selecting these and disregarding the rest, we turn them into the 

 arguments of Table 7, and we turn their corresponding arguments 

 into the entries in Table 7. 



Table 7. 

 Ordinates to Normal Curve of Distribution 

 on a scale whose unit = the Probable Error ; and in which the 100 Grades run 

 from 0° to + 50° on the one side, and to - 50° on the otber. 



Grades. 







1 



2 



3 



4 



5 



6 



7 



8 



9 







o-oo 



0-04 



0-07 



o-ii 



0-15 



0.19 



0-22 



0-26 



0-30 



0-34 



10 



0-38 



0-41 



0-45 



0-49 



53 



0-57 



0-61 



0-65 



0-69 



0'74 



20 



078 



0-82 



0-86 



0-97 



0-95 



1-00 



1'05 



1-10 



1-15 



1-20 



30 



1-25 



1-30 



1-36 



1-42 



1-47 



1-54 



1-60 



1-67 



1-74 



1-82 



40 



1-90 



1-99 



2-08 



2-19 



2-31 



2-44 



2-60 



2-79 



3-05 



3-45 



But in the Schemes, the 100 Grades do not run from— 50° through 

 0° to + 50°, but from 0° to 100°. It is therefore convenient to 

 modify Table 7 in a manner that will admit of its being used 

 directly for drawing Schemes without troublesome additions or 

 subtractions. This is done in Table 8, where the values from 

 50° onwards, and those from 50° backwards are identical with 

 those in Table 7 from 0° to ± 50°, but the first half of those 

 in Table 8 are positive and the latter half are negative. 



