144   Life and Letters of Francis Galton

law might exist for plants, which would be clear enough when a correct base line was taken; .but which would be wholly obscured when any other base line was employed.

No doubt this has been thought of, but

what I would point out, is the great facility of obtaining these sums of temperature, from

different base lines, by the use of that most   C

e'   B

ingenious little instrument of Swiss invention

4C Amsler'   A

and manufacture,s Planimeter." I   %,,, ~   W

have had it largely tested and employed at the   ~' -   - Meteorological Office of England (of which I

am one of the managing Committee) with per-   ''

feet success. A full description of its employ-   a;' ment will be found in our Meteor. Office

'Quarterly Weather Reports' of last year which are in the Geneva Observatory.

If the desire be, to try sums of the squares of excess of temperature, or of any other function, the same method of summation is of course equally applicable.

Pray excuse my prolixity; I write on the chance that our meteorological experience of rapid methods for avoiding tedious computation may prove of service in your further inquiries.

I am writing from Switzerland, from Thun, whither my wife and I are shortly going towards, the Lake of Geneva; I had your pamphlet sent to me here. Should I be in the neighbourhood of Geneva, I will certainly do myself the pleasure of calling at your house in the. hope (I fear a faint one at this season) of finding you at home.

Yours very faithfully, FRANCIS GALTON.

To M. ALPHONSE DE CANDOLLE.

GENhVE. 24 mai 1876.

MON CHER MONSIEUR Je vous envoie (sons bandes) un article sur votre interessant opuscule relatif aux jumeaux. Il vient de paraitre dans les Archives des Sciences physiques et Naturelles de mai 1876 qui se publie ici. Jai ajoute ca et Ia quelques reflexions pour montrer mieux l'interet de vos recherches. Je regrette que votre depart de la Suisse ait coincide.. aver mon excursion dans l'Engadine, ou ma sante m'oblige h aller pendant les grander chaleurs. Agreez, je vous prie, l'assurance de mes salutations empressees. ALPH. DE CANDOLLE.

It is not necessary now to settle whether the emphasis placed by Galton on heredity or by De Candolle on environment was the more scientific; they both in fact cited individual cases, and discussed, where at present we should set about measuring and statistically analysing. Nor ought we to judge a man by hastily written letters, but there is much in De Candolle's book and letters, such as. his belief-for it amounts to little more-that it was the conditions of Geneva and not the hereditary ability of the Protestant immigrants, which_ produced a scientific revival, or his faith in tales of mental or physical state during sexual union producing marked results on offspring, that will not be accepted as proven by the calmer judgment of modern science. That science would sympathise far more with Galton's suggestion that one needs "many such facts'," and that it would be better to experiment with white mice, giving the male an intoxicant before admitting him to the female. This reference to appeals to experiment is of interest, for it indicates the change that had been taking place in Galton's own procedure.

1 The assertion of De Candolle that men intoxicated at the time of coition have often produced idiots. Galton's humorous citation of Lot as evidencee to the contrary was equally valid. For a modern discussion see Eugenics Laboratory Memoirs, No. xin, pp. 19-25, Cambridge University Press.