To George Howard Darwin [after 5 April 1864?]1
Please return this paper2
French weight English grain 1. gramme = 15.44 1. milligramme = 0.0154
Now how many milligrammes (to one place of decimals) does one English grain equal?3
Enquires about the relationship of English grains to French milligrammes.
Please cite as
Darwin Correspondence Project, “Letter no. 4451F,” accessed on 31 July 2016, http://www.darwinproject.ac.uk/DCP-LETT-4451F