JDF is determined to spend the winter in the south: 'I had a serious, even alarming pulmonary inflamation at Bonn in July and August', although he is quite well now. JDF and Mrs Forbes are now on their way to Naples and Sicily, and intend to spend the spring in Rome. He is grateful for WW's 'approbation' of his book and would appreciate any comments he has concerning difficulties with his theory ['Travels through the Alps of Savoy and other parts of the Pennine Chain with Observations on the Formation of Glaciers', 1843]: 'It is very odd tha Hopkins [William Hopkins] seems to persist in considering my theory to be in opposition to his experiment whereas I have always admitted that his experiment, so far as the excessively minute gravity which the earth's heat can melt (1/25 inch per annum) can be of any avail, is very ingenious and to the point, and that it will help my Glacier down, but it is neither the cause of its moving, nor can it very materially affect the manner of it'. He would like WW to look at the models of viscous fluids which he has sent Heath [John M. heath?], since they help in understanding its structure. He has had positive reactions to his book from Bischoff, Studer and Elie de Beaumont, 'all of whom adopt my views'.