WCP4142

[1]¹

Frith Hill, Godalming.

March 7th. 1886

Dear Mr. Galton

As you have worked so much with averages exhibited diagrammatically you may perhaps have by you some diagrams illustrating the progressive accuracy of the law of deviation which you could lend me to have copied for a lantern slide for Lecture illustration. What I require is some such diagrams as the following.

See over

[2] One showing the account of deviations given by a small number of cases — 50 or 1000 for instance Another giving a large number say 1000 or more — showing that in the latter ^case there is a [one word illeg.] approach to the regular curve and also that the extremes of deviation are considerably greater. I want it to illustrate the variation of species, & to show that if we find a certain amount of irregular variation whenever we examine 20 or 50 or 100 individuals, we may confidently assume the greater extent & greater regularity of the variation if we could examine [3] [a sketch of a normal curve showing the heights of 1000 American Soldiers appears here.] thousands & millions of individuals

No doubt if you have not such diagrams yourself you can refer me to some work in which I can find them. I was delighted with your address at the Brit. Ass. on Heredity of Stature.

Yours very faithfully | Alfred R. Wallace [signature]

F. Galton Esq.