Describes scenery at Mont Blanc. Trip by mules into mountains. Barometer measurements by Charles Babbage. [Letter continues 16 Aug.:] Plans today include visit to Mar de Glace glacier. [Letter continues 20 Aug.:] Found excellent guide, Coutet, with knowledge of geology. Describes expedition to Mar de Glace glacier and JH's sketches. More barometer observations. [Letter continued 22 Aug. in Geneva:] No mail arrived from Slough. Leave tomorrow for Chambéry and Turin. Planning to leave Italy by 2 Sept.