406 Life and Letters of Francis Galton
experience " was another term for Galton's " general impressions " which had assumed a, prescriptive right not to be questioned. The Chairman administered one blow after another to the Honorary President of the Society ! The latter had asserted that " probability is the basis of Eugenics " ; the former thought he knew of a better method, though there is no evidence that he ever described it, still less attempted to apply it.
"To those, however, who are familiar with the methods of eugenic ... research the Report [that of the Eugenics Laboratory] causes no surprise at all. It simply confirms their belief that, serviceable as biometry is in its proper sphere, it has its limitations, and that a complex problem such as that of the relation of parental alcoholism to offspring is quite beyond its ken....
-"First the biometrical method is based on the `law of averages' which again is based on the 'theory of probabilities,' which again is based on mathematical calculations of a highly abstract order. From this it follows that in this particular problem, biometric research supplies no practical guide to the individual....
"I agree that some of the new technical phraseology used by the biomctricians is at first rather repelling-notably, their coefficient of correlation...."
But this, we are told, is not so bad as their probable error, which they had
to borrow ready-made from the astronomers.
"Further : the biometrical method deals only with patent and not at all with latent characteristics or qualities. Herein it differs markedly from Mendelism...."
And so the Chairman of Galton's Society wandered on, talking of matters he did not understand and of a memoir- as he admitted afterwards-he had not at the time read*. Heredity was not discussed in the memoir, and accordingly the reference to Mendelism was meaningless. What the Chairman of the Eugenics Education Society imagined would be the effect of his letter I cannot say ; that it moved Galton so that a word would have led him to resign his honorary presidency of the Society I do know. As for the members of the Eugenics Laboratory their irritation was far greater at the attack made on Galton's scientific creed than at the idle criticism of their own work. Galton himself wrote the following letter published in The Times of June 3rd
ALCOHOLISM AND OFFSPRING.
TO THE EDITOR OF THE TIMES.
. ' SIR, Mr Crackanthorpe's letter under the above heading casts doubt on the value of biometric conclusions because they are " based on the ' law of averages,' which again is based on the `theory of probabilities,' which again is based on mathematical calculations of a highly abstract order.'' So far as I can understand this account it seems to me inaccurate, but I have no idea of what is meant by "law of averages." Allow me to give my own version of biometric methods-i.e. that they are primarily based on observations, after they have been marshalled in order of their magnitudes-the little figures, say, coining first and the larger ones last-by drawing diagrams,. and by countings. This much suffices to give a correct idea of the distribution of any given set of variables ; it is also sufficient to give a fair idea of the closeness of correlation,,or of kinship, between any two sets of variables. Here exact correspondence counts as 1, no: correspondence at all as 0, and intermediate degrees are counted by intermediate decimal fractions. However, in usual biometric computations, where large numbers of figures are
* He sent round the very morning his letter appeared in The Times to 42, Rutland Gate to borrow the memoir "as he thought he ought to see it."