To Lawrence Ruck   10 January 1881

My dear Mr. Ruck

I should be very much obliged if you could obtain for me from shepherds or from your own observation a little information which will appear to you a ridiculously small point but which interests me in relation to little ledges on mountain-sides which have been observed in many parts of the world. My question is whether sheep or mountain cattle whilst grazing on a very steep slope of turf usually travel across the slope horizontally or slowly ascend it.¹ If a flock of sheep were grazing on a steep slope it would be easy to observe whether they moved up parallel to the bed of the valley, and this I wish to know. If you trust the shepherds, it would I think be advisable to ask two of them as a check, one on the other. I hope that you will forgive me for troubling you on points apparently so trivial, and I remain, my dear Mr. Ruck | Yours sincerely Charles Darwin.