Dear Sir,—

I can scarcely find words to express the extent to which I have been gratified by the opinion you have formed of my labours.¹ It is to you that I owe the circumstance of my having made a special subject of boulders. As early as 1843 I lectured in different English towns on your discoveries in the southern part of S. America, illustrating the subject by modelling a heap of sand, with salt to represent ice.² I believe Sir James Hall briefly suggested floating ice as a means of transporting stones, but you were the first to discover and explain the precise mode in which the process of transportation, from its commencement to its termination, was effected.³ My recent paper in the Quarterly Journ. Geol. Soc. was partly the outcome of a small pecuniary grant from the Government Committee of the Royal Society, which I spent in railway expenses. The Committee will be able to see most of the results in the paper (a part has not yet been published) but I cannot help wishing that you would allow me to let the secretaries know the opinion you have expressed of my labours when I next communicate with them.⁴ Should you have no objections to this you need not take the trouble to write again.

With many thanks, | I am, Dear Sir, | Your faithful Servant, | D. Mackintosh. | Lecturer on Physical Geography, Liverpool College.

P.S. I was very much interested by your statement about the Ashley Heath boulder. I fancy it must have gone from some of the mountains surrounding Ennerdale, Cumberland.⁵