To Robert Thomson   23 May 1878

Dear Sir,

I am sorry to say that so many years have elapsed since I have attended to the subject of earthquakes that I am quite incapable of expressing any opinion on your views.¹ When M^r Mallet’s paper on earthquakes, appeared, I well remember regretting that I had published any speculations on the subject, for it became clear to me that a man, to do any good work on this subject, must be deeply versed with respect to wave-motions both in solids & fluids.²

I remain dear Sir, | Yours faithfully | Charles Darwin