526 Life and Letters of Francis Galton
As regards your problem. I dare not now trust myself to analysis and to criticism of formulae; but have no doubt from elementary considerations that your results are sound. The upward and downward movements of P depend equally on A B those of A and of B. If those of A range less widely than those of B, the latter will on the whole have the predominant influence. If A does not move at all, the movements of P will be wholly due to B.
Again, the connection between small variability and small Arithmetic Mean value is clear (for symmetrical curves of frequency at least) on the supposition that negative values are impossible. A quasi-albino race (one with a small A. M. value) cannot produce individuals who are whiter than white, but if it sometimes produces such as are dark, its curve of frequency must necessarily be humped up against the axis of Y, and its positive tail can hardly be thicker at its root than
in the figure. In this case MQ3 is small (though larger than MQ,) and MQ,2 MQ3, which is
a fair measure of the s.D., must be smaller still than MQ3.
On re-reading, I fear my explanation may be found less lucid than it should be, but you will probably understand what is meant. I have written it under epistolary difficulties of table and light. I have amended it, but not well.
We are looking forward with keenest interest to a stay of Y M some days in the Lipari Islands among sulphur pumice-stone
two active volcanoes (Vulcano and Stromboli) and deported Camorrists and Maffeists. They are allowed much freedom during the day but are confined and locked in at nights. There are no robbers among them, only murderers, one of another, and they are said to be very interesting and communicative. You, with your fluent Italian and Italian sympathies, would make out a good deal from them. We are fortunate in having introductions to the principal among the few honest people who live there, as to the officer now in command and to the agent of the chief
landowner. It will be a funny experience. I expect to be housed like a pig, and not to be treated as a convict; but even they receive 50 centimes from the Government a day, which they supplement by working for wages. The weather is very variable, some sun every day; glorious sun most days. Now and then gales of wind.
The post that brought me your letter brought one also from K. Pearson, so I am posted with your Easter plans. I had hoped to be home just before Easter, but expect now to be delayed abroad a few days longer. Kindest remembrances from both of us to you both.
Very sincerely yours, FRANCIS GALTON. 42, RUTLAND GATE, S.W. April 10, 1904.
MY DEAR WELDON, I was so very sorry to miss you, and by only five minutes, yesterday. I did not dare to read your letter till this morning, being rather dangerously overworked and fearing disaster. With a lot of correspondence I begin with the least important, to ensure this not being overlooked, and end with the important. So your letter came the very last.
As regards albinos of all kinds, there is evidently an unusually close correlation between the soma and the germ (generative cell); total absence of colour in the one going with total absence in the other. When albinism is confined to the eye, the correlation is less close, but still close-ish. Perhaps the day will come when the mean correlation between soma and germ (generative cell), in respect to certain exceptional qualities, will be studied. What a puzzle it all is! The mice will be mines of. facts. Those three beautiful volumes by Amari! I am ashamed to accept so valuable a present, but will do so, and read them through, and be more and more saturated with gratitude. I have a strong leaning towards Saracens.
Eva Biggs will have told you our news. We both go into Warwickshire to-morrow for three or four days, but to different places. I to my dear old sisters, 96 and 92 respectively* (5, Bertie Terrace, Leamington); she to her sister, Mrs Bree. The cold is as much as I can bear, but I am getting acclimatised again to my native country. It would amuse you to see F. Howard
* Bessy and Emma Galton.