Letter to Sir Charles Lyell from Carlo Gemmellaro relating to the geology of the Mount Etna area. Gemmellaro states that Lyell is soon to receive a map copied from Waltershausen's marked with the profile of the extension of the 1852 lava. He mentions his brother's [Giuseppe] gratefulness for Lyell's subscription to the English house at Mount Etna and discusses lava flow at the Balyo di Aci Reale, with map. Apologises for being unable to provide Lyell with measurements for this but states that Waltershausen's measurements should be accurate as he had had the help of several scientists including Doctors Listing and Peters and Mr Ross, 16 April 1858.