For the following account of his adventures upon this occasion I am indebted to Dr. Tiarks, who, in his character of astronomical observer, superintended the expedition. In the first instance, Davy directed to be constructed a number of oblong, rectangular, thin plates of copper, the surface of which should exceed that of a square foot: in the centre of these plates was fastened a slip of copper, by means of which other pieces of copper, which had small plates of iron of various dimensions attached to them, were fixed to the plate, by merely sliding them into the groove thus prepared for their reception. The plates were all carefully weighed previously to the experiment, and the pieces of iron were considered as representing the various proportions of iron and copper surfaces within whose limits Sir H. Davy had been led, by former experiments, to expect that the best proportion would be found. These plates were afterwards slipped into wooden frames, and nailed to the ship's side, over a piece of thick canvass, for the purpose of intercepting every possible communication between them and the copper sheathing. It was proposed that, after each trip, these plates should be accurately weighed, in order to ascertain the loss which they severally might sustain from the corrosive action of the sea, while thus protected by different proportions of iron surface; and, to ensure every possible accuracy, he carried with him the excellent balance, constructed by Ramsden, which is in possession of the Royal Society. Sir H. Davy, accompanied by Lord Clifton, embarked at Greenwich on the 30th of June, and the vessel arrived at Heligoland on the 2nd of July. Here, as they remained not more than one day, the plates were not examined, although the Master expressed strong doubts as to their safety. The vessel then proceeded, by order of Sir Humphry, to Norway, a country which he was, for several reasons, very desirous of visiting, especially for the sake of determining a doubtful point in ornithology, upon which he subsequently corresponded with Professor Rheinhard, of Copenhagen. The difference of longitude, also, between that country and Greenwich, not having been accurately ascertained, offered perhaps an additional reason for thus deviating from a course which, it must be confessed, was at variance with the original plan of the expedition. After a severe gale of wind on the 4th of July, the vessel arrived, on the day following, at Rleve, near Mandal, and afterwards proceeded to this latter place, at which Davy remained for several days, during which interval the vessel made a tour to the Naze, and took in coal. On the arrival of the vessel in the port, the plates were immediately examined; but, to the great disappointment of Sir Humphry, it was discovered that every one of the protectors had been washed away, and that most of the plates had sustained considerable injury.