RECORD: Darwin, C. R. and George H. Darwin. n.d. [calculations by George H. Darwin]. CUL-DAR63.67. Edited by John van Wyhe (The Complete Work of Charles Darwin Online, http://darwin-online.org.uk/)
REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 6.2021. RN2
NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volumes CUL-DAR63, CUL-DAR64 and CUL-DAR65 contain a diverse array of materials for Darwin's research on earthworms. All of the textual items in these folders, including this one, have been transcribed in a single file: CUL-DAR63-65.
67
How did George get this
7.453 lbs per square yard brought to the surface per annum
Leith Hill
& 1/3rd of this flows down 1 inch per annum
1 inch = 1/36 yd
∴ 1/3 x 1/36 of 7.453 lbs is delivered across a linear yard per annum
This is 069 lbs per linear yard per annum
Hence the flow across a linear yard is 1.1 oz per annum
or wd fall over a full yr
Twice as much for 2 sides of valley
2.2 oz for 100 212 lbs
67v
[calculations, crossed]
Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)
File last updated 7 July, 2025