To L. C. Wedgwood   21 January [1872]¹

My dear Lucy

You are worth your weight in Gold.— I looked at a good many holes, but kept no account, & it tires my head stooping. It seems natural they sh^d come on average more often at right angles than oblique, to surface; but whether I shall be able to form a judgment I know not.—² I shall be very glad to hear any further observation, & about furrows. It is at present all working in the dark.— I am now getting more inclined to trust the result of trenches cut across old furrows on nearly level surface; or to upper & lower part of grass-slope with no old furrows.

I have had some curious observations from Wroxeter, & William is working at Stonehenge for me.—³ I hope in time to come to some approximately safe conclusion.

If worms would be so good as to come up generally at right angles to slope, it would bring the earth down grandly. By the way I suppose when you say “vertical to the slope” you mean perpendicular or at right angles to the slope. The Mathematician George⁴ says vertical always relates to the horizon, so you ought to hide your diminished head.

Yours affectionately | C. Darwin

I find after the late heavy wind & rain the soft subsided castings are much ‘blown over to leeward, even on level grass-field; the sections of all the recent castings were thus

Would you visit the common on Leith Hill when you go home, & look at castings; the late storms must have blown there with terrific force.—⁵