While making physical observations during some recent cruises on board H.M.S. “Jackal,” I was on several occasions made to feel the want of a water-bottle which could be relied on to act with precision in rough weather. Mill's slip water-bottle, which leaves nothing to be desired in its working in smooth water, at least up to depths of 400 or 500 fathoms, is apt to be closed prematurely by the jerk on the sounding line when the ship is rolling or pitching in a sea-way; and considerable doubt arises as to the point from which samples are really obtained.