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.