Comments on paper by DM ["On the parallel roads of Lochaber", (1847) Trans. R. Soc. Edinburgh 16 (1849): 395–418]. "I am not in the least convinced about the Barriers … [but] I am very much staggered in favour of the ice-lake theory of Agassiz & [William] Buckland." Will "send a letter to the Scotsman, in which I give briefly my present impression".

Cites facts mentioned in South America possibly of use to DM.

Comments on article by David Milne ["On the parallel roads of Lochaber" (1847), Trans. R. Soc. Edinburgh 16 (1849): 395–418]. Refers to his paper on Glen Roy [Collected papers 1: 87–137]. Comments on Louis Agassiz’s article ["The glacial theory and its recent progress", Edinburgh New Philos. J. 33 (1842): 217–83]. Cites his own observations on glaciers in N. Wales. Discusses possibility of ice barrier creating lake. Notes objections to theory of an ice barrier. Defends his own theory that the roads are sea-beaches. Suggests questions for further investigation.