From William Hopkins   5 May 1846

My dear Sir

The additional datum you sent to me yesterday is of no material service in your problem.¹ If your observations were sufficient to establish a general regularity in the lamination over a sufficiently wide area, (and such I think appears to be your conviction) we can scarcely resist the conclusion that the local irregularities in the laminated beds in the immediate neighbourhood of the granitic ridge (where alone I presume you found them) are due to the upheaval of that ridge. Allowing the validity of the conclusion, I should be disposed to attribute at least a considerable portion of the discordance between observed & calculated results to irregularities in the elevation of the ridge such as might arise for instance from violent lateral thrusts, the effects of which might be resisted by the flanks of the mass in an uncertain and irregular manner, and which might thus produce effects which it would be impossible to bring under the dominion of calculation. A good deal may safely be allowed to irregular action of this kind.

Let me again assure you that your problem has been no trouble to me. In a subject like Geology where it is impossible for any one to be equally acquainted with every branch of it, I hold it to be a duty to assist each other, and on that principle you will always find me ready to act.

Your’s very truly | W Hopkins