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Darwin Correspondence Project

From Leonard Darwin   7 May 1879

Brompton Barracks | Chatham


Dear Father

I am afraid that I have not been very successful in the weighing. In the first place the little bits had stuck rather firmly to the paper; it was difficult to get them off and in doing so a bit fell off the scale pan, but I am almost certain that I picked it all up. As to the weight I can only say that it was less than 1100 of a grain.1 The scale turned fairly well to the 1100 but hardly shewed any movement with the bits on it.

I enclose two sets of Dr. D’s letters, as a spare one might be useful.2 I have plenty more. Sorry not to have done better in the weighing.

Your affec son | Leonard Darwin


The substance that Leonard was trying to weigh has not been identified, but in Movement in plants, p. 147, CD noted that specks of shellac removed from the tips of two radicles of broad beans (Vicia faba) together weighed less than one hundredth of a grain. This small coating of shellac on one side of the tip of the radicle had been sufficient to cause deflection. A grain is equal to approximately 64.8 milligrams.
Leonard probably photographed the letters from Erasmus Darwin that CD had found in Robert Waring Darwin’s deeds box (see letter to Reginald Darwin, 8 April 1879 and n. 2). In Erasmus Darwin, p. 16 n., CD noted that he had other letters photographed.


Erasmus Darwin. By Ernst Krause. Translated from the German by W. S. Dallas, with a preliminary notice by Charles Darwin. London: John Murray. 1879.

Movement in plants: The power of movement in plants. By Charles Darwin. Assisted by Francis Darwin. London: John Murray. 1880.


Has been trying unsuccessfully to weigh something for CD.

Letter details

Letter no.
Leonard Darwin
Charles Robert Darwin
Sent from
Brompton Barracks, Chatham
Source of text
DAR 186: 35
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 12035,” accessed on 22 October 2021,