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Darwin Correspondence Project

From Leonard Darwin   [29 March 1872]1

Dear Father

The following is the solid content of the box, which I forgot to measure last week.

211.44 Cubic inches

Your affec son. | Leonard Darwin

Iron box of earth.

Measurement after being well dried before the fire. = 180.8 Cubic inches. This shews that it has diminished 10 per cent on the original earth, without taking into account internal shrinking, although cracks were visible on the surface.2

CD note:

March. 29.1872.


Earth dug out of ground & thrown up in fortification   increase ⁠⟨⁠of⁠⟩⁠ above 112th of bulk.—3


The date is established by CD’s note.
In Earthworms, pp. 161–2, where he gave measurements of dried earth by weight rather than volume, CD concluded that the largest castings were produced on the poorest soils, indicating that worms had to swallow a greater amount of earth on poor land in order to obtain enough food.
A further set of calculations, made by George Howard Darwin on the letter, estimates that the loss in volume of the dried earth is approximately 116.


Earthworms: The formation of vegetable mould through the action of worms: with observations on their habits. By Charles Darwin. London: John Murray. 1881.


Data relating to experiments; shrinkage of earth on drying.

Letter details

Letter no.
Leonard Darwin
Charles Robert Darwin
Sent from
Source of text
DAR 162: 75
Physical description
ALS 2pp damaged †, † (by G.H. Darwin)

Please cite as

Darwin Correspondence Project, “Letter no. 8260,” accessed on 29 May 2023,

Also published in The Correspondence of Charles Darwin, vol. 20