My dear W.

I am glad that you wish to join the Geolog. Soc^y, which well deserves support, as it has largely aided the magnificent progress of Geology, during the last $\frac{1}{2}$ century.¹

I have written for Certificate & will take all proper steps.—² The Leslie Stephen judgment will be sent you— very kind note from him: & I shall act implicity on his advice.—³

M^r Ruck is positive about sheep & cattle grazing on steep slopes always in horizontal lines, & he does not believe that the slope at bottom of valley would ever influence them.⁴ But it seems not improbable to me, that if a sheep or several first grazed, walking at the foot a steep slope & cleared the ground, or as far as it could reach; it would ascend & if it cropped all the pasturage on the next stage above it would be compelled to travel parallel to the bed of the valley.— If you visit again the spot with ledges extending parallel to the valley at about angle of 7^o, keep this notion in your mind. This action would occur only when a slope abutted on a nice level bed of valley. George & Frank think that sheep have very slightly impressed sides of Cudham valley in horizontal lines; but why they sh^d elect to walk often along the same line I cannot imagine.⁵

I have been working at some of your materials about mould & furrows, & your facts have proved very useful; but I think that I shall be able to give only a few probable conclusions.—⁶

Do not think of ledges till weather becomes niceish. It will not do to look for acacia petioles till frost quite goes & ground is soft.— Remember about dipping the buried ends for about $\frac{1}{10}$ of inch into ink. Collect all which are fairly within holes, not rejecting those which has been doubled. The doubling is new to me.—⁷

Your affectionate Father | C. Darwin

Bare places, such as walks, are best for objects drawn into burrows.—