Magnetical experiments on board H. M. iron steam vessel 'bloodhound.'

These experiments were undertaken with the view of ascertaining whether the action of steam upon the hull of an iron vessel affects a compass, properly placed, in any degree that may be of practical importance in its navigation; and also whether the keeling of the vessel produces any alteration in the deviations, or disturbs a compass so placed to any considerable extent. The former question is, from the results of these experiments, resolved in the negative; but with respect to the second, it appears that the deviations produced by keeling are very marked, and could not be safely disregarded. These observations completely confirm those already made by Mr. Walker and Commander Shaugh on board H. M. Iron Brig 'Recruit,’ Commander A. Slade, and they prove the necessity that exists for ascertaining the deviations of the compass in all ships, not only at the beginning and end of their voyage, but likewise at intermediate stations; as also constant observation of the course which the ship may be steering.