"Very little chance, doctor: I'm such a miserable object, that even disease passes by me with contempt. If I ever am in your list, I presume it will be for a case of plethora," replied Jerry, spanning his thin waist. "Young gentlemen, get down directly. What are you all doing there on the taffrail?" bawled out the first-lieutenant, who had just come up the ladder. "We've been looking at a sea-bully," said Jerry in a tone of voice sufficiently loud to excite the merriment of those about him, without being heard by the first-lieutenant. "What's the joke?" observed Mr Bully, coming aft, as the midshipmen were dispersing. "Some of Mr J---'s nonsense," replied the surgeon. This answer not being satisfactory, the first-lieutenant took it for granted, as people usually do, that the laugh was against himself, and his choler was raised against the offending party. "Mr J---! Ay, that young man thinks of anything but his duty. There he is, playing with the captain's dog; and his watch, I'll answer for it, or he would not be on deck. Mr J---," continued the first-lieutenant to Jerry, who was walking up and down to leeward, followed by a large Newfoundland dog, "is it your watch?" "Yes, sir," replied Jerry, touching his hat. "Then why are you skylarking with that dog?" "I am not skylarking with the dog, sir. He follows me up and down. I believe he takes me for a _bone_." "I am not surprised at it," replied the first-lieutenant, laughing. The surgeon, who remained abaft, was now accosted by Willy, who had been amusing himself, leaning over the side of a boat which had been lowered down, by the first-lieutenant, to examine the staying of the masts, and catching in a tin pot the various minute objects of natural history which passed by, as the frigate glided slowly along. "What shell is this, Mr Macallan, which I have picked up? It floated on the surface of the water by means of these air-bladders, which are attached to it." "That shell, Willy," replied Macallan, who, mounting his favourite hobby, immediately spouted his pompous truths, "is called by naturalists the Ianthina fragilis, perhaps the weakest and most delicate in its texture which exists, and yet the _only one_ [see note 1] which ventures to contend with the stormy ocean. The varieties of the nautili have the same property of floating on the surface of the water, but they seldom are found many miles from land. They are only coasters in comparison with this adventurous little navigator, which alone braves the Atlantic, and floats about in the same fathomless deep which is ranged by the devouring shark, and lashed by the stupendous whale. I have picked up these little sailors nearly one thousand miles from the land. Yet observe, it is his security--his tenement, of such thin texture to enable him to float with greater ease, would not be able to encounter the rippling of the wave upon the smoothest beach." "What use are they of?"