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150

Life and Letters of Francis Galton

relation"" between smallness of head and energy. Now if we distribute -40 cases uniformly among Galton's 99 individuals, we find

 
 

Heads 22" or less

Heads between

22' and 24

Heads 24" or more

Number    

13

78

8   (A)

Energetic men : observed ...

10

29

1   (B)

„   uniformly

distributed

 

5.25

31.5

3.25 (C)

A modern statistician would not be quite happy in asserting without further investigation that the owners of large heads were the less energetic. But actually the odds against (B) being a sample of (C) are about 50 to 1 and Galton's conclusion is reasonably justified. I have cited these results because, I think, Galton's statistical method does raise doubts in the minds of some readers as to its adequacy to support the superstructure'. I have been surprised myself on testing his data to find what a reasonable probability there is for the validity of his conclusions. After all the higher statistics axe only common-sense reduced to numerical appreciation, and their deductions are what "les esprits justes sentent par une sorte d'instinct, sans qu'ils puissent souvent s'en rendre compte. Galton's judgments in his

for the scientists was 22.75" + 0.50, which is not a significant difference. I deduce these from Galton's pocket-book. The following are perhaps worth extracting:

 

Subject

Subj

Head circumference

in inches

Stature in

feet and inches

Cayley    

23

5 72

Darwin   

224

6 0

Sir John Evans    

221

5 10

Francis Galton    

218

5 9

Grove    

24.0

6 0

Sir Rowland Hill    

23 7

5 7

Hooker    

211

5 102

Huxley   

23

5 10

Jevons    

23

5 52

Clerk Maxwell   

232

5 44

Owen    

23

511

Marquis of Salisbury ...

23

6 2

Herbert Spencer    

-

5 10

Spottiswoode    

223 -

5112

Sylvester    

223

-

" This is the first occasion on which I have noticed Galton using this word, of course not yet with reference to the `coefficient of correlation'.

2 I feel considerable doubts myself as to the validity of the map of the distribution of birthplaces of 100 English men of science on p. 20. It may mean nothing more than a rough density of population map. The local distribution of each type of ability in the British Isles with reference to density of population would be well worth undertaking.