Sends rock specimen for W. H. Miller. Asks JSH to see whether there is any geology in P. B. Webb and Sabin Berthelot, Histoire naturelle des Îles Canaries [1835–50]. Finds his work on geology growing so large that it will take more than one volume and asks whether this will make publication aid more difficult.
Has accepted Secretaryship of the Geological Society.
Will not come to Cambridge because "as long as I continue well I cannot bear to leave my work for half a day".