TO L.HORNER.Down, December 23rd [1859].
I must have the pleasure of thanking you for your extremely kind letter.
I am very much pleased that you approve of my book, and that you are going to pay me the extraordinary compliment of reading it twice.

I fear that it is tough reading, but it is beyond my powers to make the subject clearer.

Lyell would have done it admirably.
You must enjoy being a gentlemen at your ease, and I hear that you have returned with ardour to work at the Geological Society.

We hope in the course of the winter to persuade Mrs.Horner and yourself and daughters to pay us a visit.

Ilkley did me extraordinary good during the latter part of my stay and during my first week at home; but I have gone back latterly to my bad ways, and fear I shall never be decently well and strong.
P.S .-- When any of your party write to Mildenhall I should be much obliged if you would say to Bunbury that I hope he will not forget, whenever he reads my book, his promise to let me know what he thinks about it; for his knowledge is so great and accurate that every one must value his opinions highly.