RECORD: Darwin, C. R. and George H. Darwin. n.d. [calculations by George H. Darwin]. CUL-DAR63.67. Edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 6.2021. RN1

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.

1

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

1v

[calculations, crossed]

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Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

File last updated 25 September, 2022